有名問題・定理から学ぶ数学

Well-Known Problems and Theorems in Mathematics

数式を枠からはみ出さずに表示するためには, 画面を横に傾けてください.

数表

  • ここで使用している記号は便宜的なものであり, 一般的でない記号もある.
  • 多くの数列, 定数, 多項式には, さまざまな定義の仕方がある.
  • $1$ 列目, $1$ 行目が灰色である数列 (二項係数などの $2$ 重数列を除く) の表において, $1$ 列目の数と $1$ 行目の数の和は対応する項が数列の第何項であるかを表す.
  • 整数列については,『オンライン整数列大辞典』の整数列番号を (OEIS: A000290) のように付記した.

数列

累乗数など

平方数 $n^2$ (OEIS: A000290)
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$4$$9$$16$$25$$36$$49$$64$$81$$100$
$10$$121$$144$$169$$196$$225$$256$$289$$324$$361$$400$
$20$$441$$484$$529$$576$$625$$676$$729$$784$$841$$900$
$30$$961$$1024$$1089$$1156$$1225$$1296$$1369$$1444$$1521$$1600$
$40$$1681$$1764$$1849$$1936$$2025$$2116$$2209$$2304$$2401$$2500$
$50$$2601$$2704$$2809$$2916$$3025$$3136$$3249$$3364$$3481$$3600$
平方因数をもたない $n$ 番目の正の整数 $a_n$ (OEIS: A005117)
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$2$$3$$5$$6$$7$$10$$11$$13$$14$
$10$$15$$17$$19$$21$$22$$23$$26$$29$$30$$31$
$20$$33$$34$$35$$37$$38$$39$$41$$42$$43$$46$
$30$$47$$51$$53$$55$$57$$58$$59$$61$$62$$65$
$40$$66$$67$$69$$70$$71$$73$$74$$77$$78$$79$
$50$$82$$83$$85$$86$$87$$89$$91$$93$$94$$95$
立方数 $n^3$ (OEIS: A000578)
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$8$$27$$64$$125$$216$$343$$512$$729$$1000$
$10$$1331$$1728$$2197$$2744$$3375$$4096$$4913$$5832$$6859$$8000$
$20$$9261$$10648$$12167$$13824$$15625$$17576$$19683$$21952$$24389$$27000$
$30$$29791$$32768$$35937$$39304$$42875$$46656$$50653$$54872$$59319$$64000$
$40$$68921$$74088$$79507$$85184$$91125$$97336$$103823$$110592$$117649$$125000$
$50$$132651$$140608$$148877$$157464$$166375$$175616$$185193$$195112$$205379$$216000$

図形数

三角数 $P_{3,n}$ (OEIS: A000217)
[定義]
$P_{3,1} = 1,$ $P_{3,n+1} = P_{3,n}+n+1.$ 
[公式]
$P_{3,n} = \dfrac{n(n+1)}{2}.$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$3$$6$$10$$15$$21$$28$$36$$45$$55$
$10$$66$$78$$91$$105$$120$$136$$153$$171$$190$$210$
$20$$231$$253$$276$$300$$325$$351$$378$$406$$435$$465$
$30$$496$$528$$561$$595$$630$$666$$703$$741$$780$$820$
$40$$861$$903$$946$$990$$1035$$1081$$1128$$1176$$1225$$1275$
$50$$1326$$1378$$1431$$1485$$1540$$1596$$1653$$1711$$1770$$1830$
矩形数 $2P_{3,n}$ (OEIS: A002378)
[定義]
連続する $2$ 個の正の整数の積. 
[公式]
$2P_{3,n} = n(n+1).$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$2$$6$$12$$20$$30$$42$$56$$72$$90$$110$
$10$$132$$156$$182$$210$$240$$272$$306$$342$$380$$420$
$20$$462$$506$$552$$600$$650$$702$$756$$812$$870$$930$
$30$$992$$1056$$1122$$1190$$1260$$1332$$1406$$1482$$1560$$1640$
$40$$1722$$1806$$1892$$1980$$2070$$2162$$2256$$2352$$2450$$2550$
$50$$2652$$2756$$2862$$2970$$3080$$3192$$3306$$3422$$3540$$3660$
四角数 $P_{4,n}$ (OEIS: A000290)
[定義]
$P_{4,1} = 1,$ $P_{4,n+1} = P_{4,n}+2n+1.$ 
[公式]
$P_{4,n} = n^2.$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$4$$9$$16$$25$$36$$49$$64$$81$$100$
$10$$121$$144$$169$$196$$225$$256$$289$$324$$361$$400$
$20$$441$$484$$529$$576$$625$$676$$729$$784$$841$$900$
$30$$961$$1024$$1089$$1156$$1225$$1296$$1369$$1444$$1521$$1600$
$40$$1681$$1764$$1849$$1936$$2025$$2116$$2209$$2304$$2401$$2500$
$50$$2601$$2704$$2809$$2916$$3025$$3136$$3249$$3364$$3481$$3600$
五角数 $P_{5,n}$ (OEIS: A000326)
[定義]
$P_{5,1} = 1,$ $P_{5,n+1} = P_{5,n}+3n+1.$ 
[公式]
$P_{5,n} = \dfrac{n(3n-1)}{2}.$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$5$$12$$22$$35$$51$$70$$92$$117$$100$
$10$$145$$176$$210$$247$$287$$330$$376$$425$$477$$532$
$20$$651$$715$$782$$852$$925$$1001$$1080$$1162$$1247$$1335$
$30$$1426$$1520$$1617$$1717$$1820$$1926$$2035$$2147$$2262$$2380$
$40$$2501$$2625$$2752$$2882$$3015$$3151$$3290$$3432$$3577$$3725$
$50$$3876$$4030$$4187$$4347$$4510$$4676$$4845$$5017$$5192$$5370$
六角数 $P_{6,n}$ (OEIS: A000384)
[定義]
$P_{6,1} = 1,$ $P_{6,n+1} = P_{6,n}+4n+1.$ 
[公式]
$P_{6,n} = n(2n-1).$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$6$$15$$28$$45$$66$$91$$120$$153$$190$
$10$$231$$276$$325$$378$$435$$496$$561$$630$$703$$780$
$20$$861$$946$$1035$$1128$$1225$$1326$$1431$$1540$$1653$$1770$
$30$$1891$$2016$$2145$$2278$$2415$$2556$$2701$$2850$$3003$$3160$
$40$$3321$$3486$$3655$$3828$$4005$$4186$$4371$$4560$$4753$$4950$
$50$$5151$$5356$$5565$$5778$$5995$$6216$$6441$$6670$$6903$$7140$
中心付き三角数 $C_{3,n}$ (OEIS: A005448)
[定義]
$C_{3,1} = 1,$ $C_{3,n+1} = C_{3,n}+3n.$ 
[公式]
$C_{3,n} = \dfrac{3n(n-1)}{2}+1.$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$4$$10$$19$$31$$46$$64$$85$$109$$136$
$10$$166$$199$$235$$274$$316$$361$$409$$460$$514$$571$
$20$$631$$694$$760$$829$$901$$976$$1054$$1135$$1219$$1306$
$30$$1396$$1489$$1585$$1684$$1786$$1891$$1999$$2110$$2224$$2341$
$40$$2461$$2584$$2710$$2839$$2971$$3106$$3244$$3385$$3529$$3676$
$50$$3826$$3979$$4135$$4294$$4456$$4621$$4789$$4960$$5134$$5311$
中心付き四角数 $C_{4,n}$ (OEIS: A001844)
[定義]
$C_{4,1} = 1,$ $C_{4,n+1} = C_{4,n}+4n.$ 
[公式]
$C_{4,n} = 2n(n-1)+1.$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$5$$13$$25$$41$$61$$85$$113$$145$$181$
$10$$221$$265$$313$$365$$421$$481$$545$$613$$685$$761$
$20$$841$$925$$1013$$1105$$1201$$1301$$1405$$1513$$1625$$1741$
$30$$1861$$1985$$2113$$2245$$2381$$2521$$2665$$2813$$2965$$3121$
$40$$3281$$3445$$3613$$3785$$3961$$4141$$4325$$4513$$4705$$4901$
$50$$5101$$5305$$5513$$5725$$5941$$6161$$6385$$6613$$6845$$7081$
中心付き五角数 $C_{5,n}$ (OEIS: A005891)
[定義]
$C_{5,1} = 1,$ $C_{5,n+1} = C_{5,n}+5n.$ 
[公式]
$C_{5,n} = \dfrac{5n(n-1)}{2}+1.$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$6$$16$$31$$51$$76$$106$$141$$181$$226$
$10$$276$$331$$391$$456$$526$$601$$681$$766$$856$$951$
$20$$1051$$1156$$1266$$1381$$1501$$1626$$1756$$1891$$2031$$2176$
$30$$2326$$2481$$2641$$2806$$2976$$3151$$3331$$3516$$3706$$3901$
$40$$4101$$4306$$4516$$4731$$4951$$5176$$5406$$5641$$5881$$6126$
$50$$6376$$6631$$6891$$7156$$7426$$7701$$7981$$8266$$8556$$8851$
中心付き六角数 $C_{6,n}$ (OEIS: A003215)
[定義]
$C_{6,1} = 1,$ $C_{6,n+1} = C_{6,n}+6n.$ 
[公式]
$C_{6,n} = 3n(n-1)+1.$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$7$$19$$37$$61$$91$$127$$169$$217$$271$
$10$$331$$397$$469$$547$$631$$721$$817$$919$$1027$$1141$
$20$$1261$$1387$$1519$$1657$$1801$$1951$$2107$$2269$$2437$$2611$
$30$$2791$$2977$$3169$$3367$$3571$$3781$$3997$$4219$$4447$$4681$
$40$$4921$$5167$$5419$$5677$$5941$$6211$$6487$$6769$$7057$$7351$
$50$$7651$$7957$$8269$$8587$$8911$$9241$$9577$$9919$$10267$$10621$
三角錐数 $S_{3,n}$ (OEIS: A000292)
[定義]
$S_{3,n} = P_{3,1}+\cdots +P_{3,n}.$ 
[公式]
$S_{3,n} = \dfrac{n(n+1)(n+2)}{6}.$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$4$$10$$20$$35$$56$$84$$120$$165$$220$
$10$$286$$364$$455$$560$$680$$816$$969$$1140$$1330$$1540$
$20$$1771$$2024$$2300$$2600$$2925$$3276$$3654$$4060$$4495$$4960$
$30$$5456$$5984$$6545$$7140$$7770$$8436$$9139$$9880$$10660$$11480$
$40$$12341$$13244$$14190$$15180$$16215$$17296$$18424$$19600$$20825$$22100$
$50$$23426$$24804$$26235$$27720$$29260$$30856$$32509$$34220$$35990$$37820$
四角錐数 $S_{4,n}$ (OEIS: A000330)
[定義]
$S_{4,n} = P_{4,1}+\cdots +P_{4,n}.$ 
[公式]
$S_{4,n} = \dfrac{n(n+1)(2n+1)}{6}.$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$5$$14$$30$$55$$91$$140$$204$$285$$385$
$10$$506$$650$$819$$1015$$1240$$1496$$1785$$2109$$2470$$2870$
$20$$3311$$3795$$4324$$4900$$5525$$6201$$6930$$7714$$8555$$9455$
$30$$10416$$11440$$12529$$13685$$14910$$16206$$17575$$19019$$20540$$22140$
$40$$23821$$25585$$27434$$29370$$31395$$33511$$35720$$38024$$40425$$42925$
$50$$45526$$48230$$51039$$53955$$56980$$60116$$63365$$66729$$70210$$73810$
五角錐数 $S_{5,n}$ (OEIS: A002411)
[定義]
$S_{5,n} = P_{5,1}+\cdots +P_{5,n}.$ 
[公式]
$S_{5,n} = \dfrac{n^2(n+1)}{2}.$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$6$$18$$40$$75$$126$$196$$288$$405$$550$
$10$$726$$936$$1183$$1470$$1800$$2176$$2601$$3078$$3610$$4200$
$20$$4851$$5566$$6348$$7200$$8125$$9126$$10206$$11368$$12615$$13950$
$30$$15376$$16896$$18513$$20230$$22050$$23976$$26011$$28158$$30420$$32800$
$40$$35301$$37926$$40678$$43560$$46575$$49726$$53016$$56448$$60025$$63750$
$50$$67626$$71656$$75843$$80190$$84700$$89376$$94221$$99238$$104430$$109800$
六角錐数 $S_{6,n}$ (OEIS: A002412)
[定義]
$S_{6,n} = P_{6,1}+\cdots +P_{6,n}.$ 
[公式]
$S_{6,n} = \dfrac{n(n+1)(4n-1)}{6}.$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$7$$22$$50$$95$$161$$252$$372$$525$$715$
$10$$946$$1222$$1547$$1925$$2360$$2856$$3417$$4047$$4750$$5530$
$20$$6391$$7337$$8372$$9500$$10725$$12051$$13482$$15022$$16675$$18445$
$30$$20336$$22352$$24497$$26775$$29190$$31746$$34447$$37297$$40300$$43460$
$40$$46781$$50267$$53922$$57750$$61755$$65941$$70312$$74872$$79625$$84575$
$50$$89726$$95082$$100647$$106425$$112420$$118636$$125077$$131747$$138650$$145790$

素数

$n$ 番目の素数 $p_n$ (OEIS: A000040)
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$2$$3$$5$$7$$11$$13$$17$$19$$23$$29$
$10$$31$$37$$41$$43$$47$$53$$59$$61$$67$$71$
$20$$73$$79$$83$$89$$97$$101$$103$$107$$109$$113$
$30$$127$$131$$137$$139$$149$$151$$157$$163$$167$$173$
$40$$179$$181$$191$$193$$197$$199$$211$$223$$227$$229$
$50$$233$$239$$241$$251$$257$$263$$269$$271$$277$$281$
$60$$283$$293$$307$$311$$313$$317$$331$$337$$347$$349$
$70$$353$$359$$367$$373$$379$$383$$389$$397$$401$$409$
$80$$419$$421$$431$$433$$439$$443$$449$$457$$461$$463$
$90$$467$$479$$487$$491$$499$$503$$509$$521$$523$$541$
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$100$$547$$557$$563$$569$$571$$577$$587$$593$$599$$601$
$110$$607$$613$$617$$619$$631$$641$$643$$647$$653$$659$
$120$$661$$673$$677$$683$$691$$701$$709$$719$$727$$733$
$130$$739$$743$$751$$757$$761$$769$$773$$787$$797$$809$
$140$$811$$821$$823$$827$$829$$839$$853$$857$$859$$863$
$150$$877$$881$$883$$887$$907$$911$$919$$929$$937$$941$
$160$$947$$953$$967$$971$$977$$983$$991$$997$$1009$$1013$
$170$$1019$$1021$$1031$$1033$$1039$$1049$$1051$$1061$$1063$$1069$
$180$$1087$$1091$$1093$$1097$$1103$$1109$$1117$$1123$$1129$$1151$
$190$$1153$$1163$$1171$$1181$$1187$$1193$$1201$$1213$$1217$$1223$
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$200$$1229$$1231$$1237$$1249$$1259$$1277$$1279$$1283$$1289$$1291$
$210$$1297$$1301$$1303$$1307$$1319$$1321$$1327$$1361$$1367$$1373$
$220$$1381$$1399$$1409$$1423$$1427$$1429$$1433$$1439$$1447$$1451$
$230$$1453$$1459$$1471$$1481$$1483$$1487$$1489$$1493$$1499$$1511$
$240$$1523$$1531$$1543$$1549$$1553$$1559$$1567$$1571$$1579$$1583$
$250$$1597$$1601$$1607$$1609$$1613$$1619$$1621$$1627$$1637$$1657$
$260$$1663$$1667$$1669$$1693$$1697$$1699$$1709$$1721$$1723$$1733$
$270$$1741$$1747$$1753$$1759$$1777$$1783$$1787$$1789$$1801$$1811$
$280$$1823$$1831$$1847$$1861$$1867$$1871$$1873$$1877$$1879$$1889$
$290$$1901$$1907$$1913$$1931$$1933$$1949$$1951$$1973$$1979$$1987$
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$300$$1993$$1997$$1999$$2003$$2011$$2017$$2027$$2029$$2039$$2053$
$310$$2063$$2069$$2081$$2083$$2087$$2089$$2099$$2111$$2113$$2129$
$320$$2131$$2137$$2141$$2143$$2153$$2161$$2179$$2203$$2207$$2213$
$330$$2221$$2237$$2239$$2243$$2251$$2267$$2269$$2273$$2281$$2287$
$340$$2293$$2297$$2309$$2311$$2333$$2339$$2341$$2347$$2351$$2357$
$350$$2371$$2377$$2381$$2383$$2389$$2393$$2399$$2411$$2417$$2423$
$360$$2437$$2441$$2447$$2459$$2467$$2473$$2477$$2503$$2521$$2531$
$370$$2539$$2543$$2549$$2551$$2557$$2579$$2591$$2593$$2609$$2617$
$380$$2621$$2633$$2647$$2657$$2659$$2663$$2671$$2677$$2683$$2687$
$390$$2689$$2693$$2699$$2707$$2711$$2713$$2719$$2729$$2731$$2741$
メルセンヌ素数 (指数 → OEIS: A000043)
[定義]
メルセンヌ数 $2^p-1$ ($p$: 正の整数) の形の $n$ 番目の素数.
[性質]
メルセンヌ数 $2^p-1$ が素数ならば, $p$ は素数 (逆は偽).
メルセンヌ素数 $2^p-1$ は, 偶数の完全数 $2^{p-1}(2^p-1)$ と $1$ 対 $1$ に対応する.
[注意]
下表において, 近似値の小数点以下は切り捨てである.
$n$$+1$$+2$$+3$$+4$$+5$
$0$$2^2-1$
$= 3$
$2^3-1$
$= 7$
$2^5-1$
$= 31$
$2^7-1$
$= 127$
$2^{13}-1$
$= 8191$
$5$$2^{17}-1$
$= 131071$
$2^{19}-1$
$= 524287$
$2^{31}-1$
$= 2147483647$
$2^{61}-1$
$\fallingdotseq\! 2\!\times\!10^{18}$
$2^{89}-1$
$\fallingdotseq\! 6\!\times\!10^{26}$
$10$$2^{107}-1$
$\fallingdotseq\! 1\!\times\!10^{32}$
$2^{127}-1$
$\fallingdotseq\! 1\!\times\!10^{38}$
$2^{521}-1$
$\fallingdotseq\! 6\!\times\!10^{156}$
$2^{607}-1$
$\fallingdotseq\! 5\!\times\!10^{182}$
$2^{1279}-1$
$\fallingdotseq\! 1\!\times\!10^{385}$
$15$$2^{2203}-1$
$\fallingdotseq\! 1\!\times\!10^{663}$
$2^{2281}-1$
$\fallingdotseq\! 4\!\times\!10^{686}$
$2^{3217}-1$
$\fallingdotseq\! 2\!\times\!10^{968}$
$2^{4253}-1$
$\fallingdotseq\! 1\!\times\!10^{1280}$
$2^{4423}-1$
$\fallingdotseq\! 2\!\times\!10^{1331}$
$20$$2^{9689}-1$
$\fallingdotseq\! 4\!\times\!10^{2916}$
$2^{9941}-1$
$\fallingdotseq\! 3\!\times\!10^{2992}$
$2^{11213}-1$
$\fallingdotseq\! 2\!\times\!10^{3375}$
$2^{19937}-1$
$\fallingdotseq\! 4\!\times\!10^{6001}$
$2^{21701}-1$
$\fallingdotseq\! 4\!\times\!10^{6532}$
$25$$2^{23209}-1$
$\fallingdotseq\! 4\!\times\!10^{6986}$
$2^{44497}-1$
$\fallingdotseq\! 8\!\times\!10^{13394}$
$2^{86243}-1$
$\fallingdotseq\! 5\!\times\!10^{25961}$
$2^{110503}-1$
$\fallingdotseq\! 5\!\times\!10^{33264}$
$2^{132049}-1$
$\fallingdotseq\! 5\!\times\!10^{39750}$
$30$$2^{216091}-1$
$\fallingdotseq\! 7\!\times\!10^{65049}$
$2^{756839}-1$
$\fallingdotseq\! 1\!\times\!10^{227831}$
$2^{859433}-1$
$\fallingdotseq\! 1\!\times\!10^{258715}$
$2^{1257787}-1$
$\fallingdotseq\! 4\!\times\!10^{378631}$
$2^{1398269}-1$
$\fallingdotseq\! 8\!\times\!10^{420920}$
$35$$2^{2976221}-1$
$\fallingdotseq\! 6\!\times\!10^{895931}$
$2^{3021377}-1$
$\fallingdotseq\! 1\!\times\!10^{909525}$
$2^{6972593}-1$
$\fallingdotseq\! 4\!\times\!10^{2098959}$
$2^{13466917}-1$
$\fallingdotseq\! 9\!\times\!10^{4053945}$
$2^{20996011}-1$
$\fallingdotseq\! 1\!\times\!10^{6320429}$
$40$$2^{24036583}-1$
$\fallingdotseq\! 2\!\times\!10^{7235732}$
$2^{25964951}-1$
$\fallingdotseq\! 1\!\times\!10^{7816229}$
$2^{30402457}-1$
$\fallingdotseq\! 3\!\times\!10^{9152051}$
$2^{32582657}-1$
$\fallingdotseq\! 1\!\times\!10^{9808357}$
$2^{37156667}-1$
$\fallingdotseq\! 2\!\times\!10^{11185271}$
$45$$2^{42643801}-1$
$\fallingdotseq\! 1\!\times\!10^{12837063}$
$2^{43112609}-1$
$\fallingdotseq\! 3\!\times\!10^{12978188}$
$2^{57885161}-1$
$\fallingdotseq\! 5\!\times\!10^{17425169}$
$?$$?$
フェルマー素数 (OEIS: A019434)
[定義]
フェルマー数 $F_n = 2^{2^n}+1$ $(n \geqq 0)$ の形の素数.
$n$$+0$$+1$$+2$$+3$$+4$
$0$$2^{2^0}+1$
$= 3$
$2^{2^1}+1$
$= 5$
$2^{2^2}+1$
$= 17$
$2^{2^3}+1$
$= 257$
$2^{2^4}+1$
$= 65537$
作図可能な正多角形の頂点の個数 (OEIS: A003401)
[定義]
目盛りのない定規とコンパスのみで作図可能な正多角形の頂点の個数.
[性質]
すべて $2^iF_1\cdots F_r$ ($i,$ $r$: 非負整数, $F_1,$ $\cdots,$ $F_r$: 相異なるフェルマー素数) の形に表される.
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$3$$4$$5$$6$$8$$10$$12$$15$$16$$17$
$10$$20$$24$$30$$32$$34$$40$$48$$51$$60$$64$
ピアポント素数 (OEIS: A005109)
[定義]
$2^u3^v+1$ ($u,$ $v$: 非負整数) の形の素数.
$n$$+1$$+2$$+3$$+4$$+5$
$0$$2$$3$$5$$7$$13$
$5$$17$$19$$37$$73$$97$
$10$$109$$163$$193$$257$$433$
$15$$487$$577$$769$$1153$$1297$
$20$$1459$$2593$$2917$$3457$$3889$
$25$$10369$$12289$$17497$$18433$$39367$
$30$$52489$$65537$$139969$$147457$$209953$
$35$$331777$$472393$$629857$$746497$$786433$
折り紙で作図可能な正多角形の頂点の個数 (OEIS: 該当なし)
[定義]
道具を使わずに折り紙で作図可能な正多角形の頂点の個数.
[性質]
すべて $2^i3^jP_1\cdots P_r$ ($i,$ $j,$ $r$: 非負整数, $P_1,$ $\cdots,$ $P_r$: 相異なるピアポント素数) の形に表される.
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$3$$4$$5$$6$$7$$8$$9$$10$$12$$13$
$10$$14$$15$$16$$17$$18$$19$$20$$21$$24$$26$
$20$$27$$28$$30$$32$$34$$35$$36$$37$$38$$39$
$30$$40$$42$$45$$48$$51$$52$$54$$56$$57$$60$
$n$ 番目の階乗素数 (OEIS: A002981, A002982; A088332, A055490)
[定義]
$k!\pm 1$ ($k$: 正の整数) の形の素数.
$n$$+1$$+2$$+3$$+4$$+5$
$0$$1!+1$
$= 2$
$2!+1$
$= 3$
$3!-1$
$= 5$
$3!+1$
$= 7$
$4!-1$
$= 23$
$5$$6!-1$
$= 719$
$7!-1$
$= 5039$
$11!+1$
$= 39916801$
$12!-1$
$= 479001599$
$14!-1$
$\fallingdotseq 8\times 10^{10}$
$10$$27!+1$
$\fallingdotseq 1\times 10^{28}$
$30!-1$
$\fallingdotseq 2\times 10^{32}$
$32!-1$
$\fallingdotseq 2\times 10^{35}$
$33!-1$
$\fallingdotseq 8\times 10^{36}$
$37!+1$
$\fallingdotseq 1\times 10^{43}$
$15$$38!-1$
$\fallingdotseq 5\times 10^{44}$
$41!+1$
$\fallingdotseq 3\times 10^{49}$
$73!+1$
$\fallingdotseq 4\times 10^{105}$
$77!+1$
$\fallingdotseq 1\times 10^{113}$
$94!-1$
$\fallingdotseq 1\times 10^{146}$
$20$$116!+1$
$\fallingdotseq 3\times 10^{190}$
$154!+1$
$\fallingdotseq 3\times 10^{271}$
$166!-1$
$\fallingdotseq 9\times 10^{297}$
$320!+1$
$\fallingdotseq 2\times 10^{664}$
$324!-1$
$\fallingdotseq 2\times 10^{674}$
$25$$340!+1$
$\fallingdotseq 5\times 10^{714}$
$379!-1$
$\fallingdotseq 2\times 10^{814}$
$399!+1$
$\fallingdotseq 1\times 10^{866}$
$427!+1$
$\fallingdotseq 2\times 10^{939}$
$469!-1$
$\fallingdotseq 6\times 10^{1050}$
$30$$546!-1$
$\fallingdotseq 1\times 10^{1259}$
$872!+1$
$\fallingdotseq 1\times 10^{2187}$
$974!-1$
$\fallingdotseq 5\times 10^{2489}$
$1477!+1$
$\fallingdotseq 5\times 10^{4041}$
$1963!-1$
$\fallingdotseq 3\times 10^{5613}$
$35$$3507!-1$
$\fallingdotseq 1\times 10^{10911}$
$3610!-1$
$\fallingdotseq 9\times 10^{11276}$
$6380!+1$
$\fallingdotseq 1\times 10^{21506}$
$6917!-1$
$\fallingdotseq 1\times 10^{23559}$
$21480!-1$
$\fallingdotseq 1\times 10^{83726}$
$40$$26951!+1$
$\fallingdotseq 2\times 10^{107706}$
$34790!-1$
$\fallingdotseq 5\times 10^{142890}$
$94550!-1$
$\fallingdotseq 1\times 10^{429389}$
$103040!-1$
$\fallingdotseq 2\times 10^{471793}$
$110059!+1$
$\fallingdotseq 1\times 10^{507081}$
$45$$147855!-1$
$\fallingdotseq 3\times 10^{700176}$
$150209!+1$
$\fallingdotseq 2\times 10^{712354}$
$208003!-1$
$\fallingdotseq 8\times 10^{1015842}$
$288465!+1$
$\fallingdotseq 1\times 10^{1449770}$
$?$
カレン素数 (OEIS: A050920, A005849)
[定義]
$k\cdot 2^k+1$ ($k$: 正の整数) の形の素数.
$n$$+1$$+2$$+3$$+4$$+5$
$0$$1\cdot 2^1+1$
$= 3$
$141\cdot 2^{141}+1$
$\fallingdotseq 3\times 10^{44}$
$4713\cdot 2^{4713}+1$
$\fallingdotseq 2\times 10^{1422}$
$5795\cdot 2^{5795}+1$
$\fallingdotseq 1\times 10^{1748}$
$6611\cdot 2^{6611}+1$
$\fallingdotseq 8\times 10^{1993}$
$5$$18496\cdot 2^{18496}+1$
$\fallingdotseq 1\times 10^{5572}$
$32292\cdot 2^{32292}+1$
$\fallingdotseq 2\times 10^{9725}$
$32469\cdot 2^{32469}+1$
$\fallingdotseq 4\times 10^{9778}$
$59656\cdot 2^{59656}+1$
$\fallingdotseq 1\times 10^{17963}$
$90825\cdot 2^{90825}+1$
$\fallingdotseq 1\times 10^{27346}$
$10$$262419\cdot 2^{262419}+1$
$\fallingdotseq 2\times 10^{79001}$
$361275\cdot 2^{361275}+1$
$\fallingdotseq 1\times 10^{108760}$
$481899\cdot 2^{481899}+1$
$\fallingdotseq 5\times 10^{145071}$
$1354828\cdot 2^{1354828}+1$
$\fallingdotseq 9\times 10^{407849}$
$6328548\cdot 2^{6328548}+1$
$\fallingdotseq 3\times 10^{1905089}$
$15$$6679881\cdot 2^{6679881}+1$
$\fallingdotseq 3\times 10^{7925689}$
$?$$?$$?$$?$
ウッダル素数 (OEIS: A050918, A002234)
[定義]
$k\cdot 2^k-1$ ($k$: 正の整数) の形の素数.
$n$$+1$$+2$$+3$$+4$$+5$
$0$$2\cdot 2^2-1$
$= 7$
$3\cdot 2^3-1$
$= 23$
$6\cdot 2^6-1$
$= 383$
$30\cdot 2^{30}-1$
$\fallingdotseq 3\times 10^{10}$
$75\cdot 2^{75}-1$
$\fallingdotseq 2\times 10^{24}$
$5$$81\cdot 2^{81}-1$
$\fallingdotseq 1\times 10^{26}$
$115\cdot 2^{115}-1$
$\fallingdotseq 4\times 10^{36}$
$123\cdot 2^{123}-1$
$\fallingdotseq 1\times 10^{39}$
$249\cdot 2^{249}-1$
$\fallingdotseq 2\times 10^{77}$
$362\cdot 2^{362}-1$
$\fallingdotseq 3\times 10^{111}$
$10$$384\cdot 2^{384}-1$
$\fallingdotseq 1\times 10^{118}$
$462\cdot 2^{462}-1$
$\fallingdotseq 5\times 10^{141}$
$512\cdot 2^{512}-1$
$\fallingdotseq 6\times 10^{156}$
$751\cdot 2^{751}-1$
$\fallingdotseq 8\times 10^{228}$
$822\cdot 2^{822}-1$
$\fallingdotseq 2\times 10^{250}$
$15$$5312\cdot 2^{5312}-1$
$\fallingdotseq 6\times 10^{1602}$
$7755\cdot 2^{7755}-1$
$\fallingdotseq 2\times 10^{2338}$
$9531\cdot 2^{9531}-1$
$\fallingdotseq 1\times 10^{2873}$
$12379\cdot 2^{12379}-1$
$\fallingdotseq 3\times 10^{3730}$
$15822\cdot 2^{15822}-1$
$\fallingdotseq 1\times 10^{4767}$
$20$$18885\cdot 2^{18885}-1$
$\fallingdotseq 1\times 10^{5689}$
$22971\cdot 2^{22971}-1$
$\fallingdotseq 2\times 10^{6919}$
$23005\cdot 2^{23005}-1$
$\fallingdotseq 3\times 10^{6929}$
$98726\cdot 2^{98726}-1$
$\fallingdotseq 3\times 10^{29724}$
$143018\cdot 2^{143018}-1$
$\fallingdotseq 7\times 10^{43057}$
$25$$151023\cdot 2^{151023}-1$
$\fallingdotseq 4\times 10^{45467}$
$667071\cdot 2^{667071}-1$
$\fallingdotseq 1\times 10^{200814}$
$1195203\cdot 2^{1195203}-1$
$\fallingdotseq 1\times 10^{359798}$
$1268979\cdot 2^{1268979}-1$
$\fallingdotseq 7\times 10^{382006}$
$1467763\cdot 2^{1467763}-1$
$\fallingdotseq 7\times 10^{441846}$
$30$$2013992\cdot 2^{2013992}-1$
$\fallingdotseq 2\times 10^{606278}$
$2367906\cdot 2^{2367906}-1$
$\fallingdotseq 1\times 10^{712817}$
$3752948\cdot 2^{3752948}-1$
$\fallingdotseq 3\times 10^{1129756}$
$17016602\cdot 2^{17016602}-1$
$\fallingdotseq 7\times 10^{5122514}$
$?$
$n$ 番目のプロス素数 (OEIS: A080076)
[定義]
$k\cdot 2^m+1$ ($m$: 正の整数, $k$: $2^m$ 未満の正の奇数) の形の $n$ 番目の素数.
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$3$$5$$13$$17$$41$$97$$113$$193$$241$$257$
$10$$353$$449$$577$$641$$673$$769$$929$$1153$$1217$$1409$
$20$$1601$$2113$$2689$$2753$$3137$$3329$$3457$$4481$$4993$$6529$
$30$$7297$$7681$$7937$$9473$$9601$$9857$$10369$$10753$$11393$$11777$
$n$ 番目の双子素数 $(p_n,p_n+2)$ (OEIS: A001359, A006512)
[定義]
$p$ も $p+2$ も素数であるとき, 素数の対 $(p,p+2)$ を双子素数と呼ぶ.
$n$$1$$2$$3$$4$$5$$6$$7$$8$$9$$10$
$p_n$$3$$5$$11$$17$$29$$41$$59$$71$$101$$107$
$p_n+2$$5$$7$$13$$19$$31$$43$$61$$73$$103$$109$
$n$$11$$12$$13$$14$$15$$16$$17$$18$$19$$20$
$p_n$$137$$149$$179$$191$$197$$227$$239$$269$$281$$311$
$p_n+2$$139$$151$$181$$193$$199$$229$$241$$271$$283$$313$
$n$$21$$22$$23$$24$$25$$26$$27$$28$$29$$30$
$p_n$$347$$419$$431$$461$$521$$569$$599$$617$$641$$659$
$p_n+2$$349$$421$$433$$463$$523$$571$$601$$619$$643$$661$
$n$$31$$32$$33$$34$$35$$36$$37$$38$$39$$40$
$p_n$$809$$821$$827$$857$$881$$1019$$1031$$1049$$1061$$1091$
$p_n+2$$811$$823$$829$$859$$883$$1021$$1033$$1051$$1063$$1093$
$n$ 番目のソフィー・ジェルマン素数 $p_n,$ 安全素数 $q_n$ (OEIS: A005384, A005385)
[定義]
$p$ も $2p+1$ も素数であるとき, $p$ をソフィー・ジェルマン素数, $2p+1$ を安全素数と呼ぶ.
$n$$1$$2$$3$$4$$5$$6$$7$$8$$9$$10$
$p_n$$2$$3$$5$$11$$23$$29$$41$$53$$83$$89$
$q_n$$5$$7$$11$$23$$47$$59$$83$$107$$167$$179$
$n$$11$$12$$13$$14$$15$$16$$17$$18$$19$$20$
$p_n$$113$$131$$173$$179$$191$$233$$239$$251$$281$$293$
$q_n$$227$$263$$347$$359$$383$$467$$479$$503$$563$$587$
$n$$21$$22$$23$$24$$25$$26$$27$$28$$29$$30$
$p_n$$359$$419$$431$$443$$491$$509$$593$$641$$653$$659$
$q_n$$719$$839$$863$$887$$983$$1019$$1187$$1283$$1307$$1319$
$n$$31$$32$$33$$34$$35$$36$$37$$38$$39$$40$
$p_n$$683$$719$$743$$761$$809$$911$$953$$1013$$1019$$1031$
$q_n$$1367$$1439$$1487$$1523$$1619$$1823$$1907$$2027$$2039$$2063$
$n$ 番目のフォーチュン数 (OEIS: A005235)
[定義]
$n$ 番目の素数 $p_n$ の素数階乗に加えて素数になるような $1$ より大きい最小の整数. 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$3$$5$$7$$13$$23$$17$$19$$23$$37$$61$
$10$$67$$61$$71$$47$$107$$59$$61$$109$$89$$103$
$20$$79$$151$$197$$101$$103$$233$$223$$127$$223$$191$
$30$$163$$229$$643$$239$$157$$167$$439$$239$$199$$191$
$40$$199$$383$$233$$751$$313$$773$$607$$313$$383$$293$
$50$$443$$331$$283$$277$$271$$401$$307$$331$$379$$491$

素数の類似の概念

$n$ 番目の幸運数 (OEIS: A000959)
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$3$$7$$9$$13$$15$$21$$25$$31$$33$
$10$$37$$43$$49$$51$$63$$67$$69$$73$$75$$79$
$20$$87$$93$$99$$105$$111$$115$$127$$129$$133$$135$
$30$$141$$151$$159$$163$$169$$171$$189$$193$$195$$201$
$40$$205$$211$$219$$223$$231$$235$$237$$241$$259$$261$
$50$$267$$273$$283$$285$$289$$297$$303$$307$$319$$321$
$n$ 番目の幸運素数 (OEIS: A031157)
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$3$$7$$13$$31$$37$$43$$67$$73$$79$$127$
$10$$151$$163$$193$$211$$223$$241$$283$$307$$331$$349$
$20$$367$$409$$421$$433$$463$$487$$541$$577$$601$$613$
$30$$619$$631$$643$$673$$727$$739$$769$$787$$823$$883$
$40$$937$$991$$997$$1009$$1021$$1039$$1087$$1093$$1117$$1123$
$50$$1201$$1231$$1249$$1291$$1303$$1459$$1471$$1543$$1567$$1579$
$n$ 番目の実際数 (OEIS: A005153)
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$2$$4$$6$$8$$12$$16$$18$$20$$24$
$10$$28$$30$$32$$36$$40$$42$$48$$54$$56$$60$
$20$$64$$66$$72$$78$$80$$84$$88$$90$$96$$100$
$30$$104$$108$$112$$120$$126$$128$$132$$140$$144$$150$
$40$$156$$160$$162$$168$$176$$180$$192$$196$$198$$200$
$50$$204$$208$$210$$216$$220$$224$$228$$234$$240$$252$
$n$ 番目の原始的実際数 (OEIS: A267124)
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$2$$6$$20$$28$$30$$42$$66$$78$$88$
$10$$104$$140$$204$$210$$220$$228$$260$$272$$276$$304$
$20$$306$$308$$330$$340$$342$$348$$364$$368$$380$$390$
$30$$414$$460$$462$$464$$476$$496$$510$$522$$532$$546$
$40$$558$$570$$580$$620$$644$$666$$690$$714$$740$$744$
$50$$798$$812$$820$$858$$860$$868$$870$$888$$930$$966$

約数

正の整数 $n$ の正の約数の個数 $d(n)$ (OEIS: A000005)
[公式]
正の整数 $n$ が $n = p_1{}^{e_1}\cdots p_r{}^{e_r}$ ($p_k$: 相異なる素数, $e_k$: 非負整数) と素因数分解されるとき, $d(n) = (e_1+1)\cdots (e_r+1).$
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$2$$2$$3$$2$$4$$2$$4$$3$$4$
$10$$2$$6$$2$$4$$4$$5$$2$$6$$2$$6$
$20$$4$$4$$2$$8$$3$$4$$4$$6$$2$$8$
$30$$2$$6$$4$$4$$4$$9$$2$$4$$4$$8$
$40$$2$$8$$2$$6$$6$$4$$2$$10$$3$$6$
$50$$4$$6$$2$$8$$4$$8$$4$$4$$2$$12$
正の整数 $n$ の正の約数の総和 $\sigma (n)$ (OEIS: A000203)
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$3$$4$$7$$6$$12$$8$$15$$13$$18$
$10$$12$$28$$14$$24$$24$$31$$18$$39$$20$$42$
$20$$32$$36$$24$$60$$31$$42$$40$$56$$30$$72$
$30$$32$$63$$48$$54$$48$$91$$38$$60$$56$$90$
$40$$42$$96$$44$$84$$78$$72$$48$$124$$57$$93$
$50$$72$$98$$54$$120$$72$$120$$80$$90$$60$$168$
正の整数 $n$ の相異なる素因数の個数 $\omega (n)$ (OEIS: A001221)
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$0$$1$$1$$1$$1$$2$$1$$1$$1$$2$
$10$$1$$2$$1$$2$$2$$1$$1$$2$$1$$2$
$20$$2$$2$$1$$2$$1$$2$$1$$2$$1$$3$
$30$$1$$1$$2$$2$$2$$2$$1$$2$$2$$2$
$40$$1$$3$$1$$2$$2$$2$$1$$2$$1$$2$
$50$$2$$2$$1$$2$$2$$2$$2$$2$$1$$3$
正の整数 $n$ の重複度込みの素因数の個数 $\mathit\Omega\,(n)$ (OEIS: A001222)
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$0$$1$$1$$2$$1$$2$$1$$3$$2$$2$
$10$$1$$3$$1$$2$$2$$4$$1$$3$$1$$3$
$20$$2$$2$$1$$4$$2$$2$$3$$3$$1$$3$
$30$$1$$5$$2$$2$$2$$4$$1$$2$$2$$4$
$40$$1$$3$$1$$3$$3$$2$$1$$5$$2$$3$
$50$$2$$3$$1$$4$$2$$4$$2$$2$$1$$4$
オイラーの $\varphi$ 関数の値 $\varphi (n)$ (OEIS: A000010)
[定義]
正の整数 $n$ に対して, $n$ と互いに素な $n$ 以下の正の整数の個数を $\varphi (n)$ で表す. これは, $n$ を法とする既約剰余類群 $(\mathbb Z/n\mathbb Z)^\times$ の位数に他ならない.
[公式]
正の整数 $n$ が $n = p_1{}^{e_1}\cdots p_r{}^{e_r}$ ($p_k$: 相異なる素数, $e_k$: 非負整数) と素因数分解されるとき, $\varphi (n) = (p_1{}^{e_1}-p_1{}^{e_1-1})\cdots (p_r{}^{e_r}-p_r{}^{e_r-1}) = n(1-p_1{}^{-1})\cdots (1-p_r{}^{-1}).$
[性質]
正の整数 $n$ と互いに素な整数 $a$ に対して, $a^{\varphi (n)} \equiv 1\ (\text{mod}\ n).$
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$1$$2$$2$$4$$2$$6$$4$$6$$4$
$10$$10$$4$$12$$6$$8$$8$$16$$6$$18$$8$
$20$$12$$10$$22$$8$$20$$12$$18$$12$$28$$8$
$30$$30$$16$$20$$16$$24$$12$$36$$18$$24$$16$
$40$$40$$12$$42$$20$$24$$22$$46$$16$$42$$20$
$50$$32$$24$$52$$18$$40$$24$$36$$28$$58$$16$
カーマイケルの $\lambda$ 関数の値 $\lambda (n)$ (OEIS: A002322)
[定義]
正の整数 $n$ と互いに素なすべての正の整数 $a$ に対して $a^l \equiv 1\ (\text{mod}\ n)$ を満たす正の整数 $l$ の最小値を $\lambda (n)$ で表す.
[公式]
$n = 1,$ $2,$ $4$ または $n$ が奇素数の累乗であるとき $\lambda (n) = \varphi (n),$
$n$ が $8$ 以上の $2$ の累乗であるとき $\lambda (n) = \varphi (n)/2,$
$n$ が相異なる素数の累乗 $n_1,$ $\cdots,$ $n_r$ の積であるとき, $\lambda (n)$ は $\lambda (n_1),$ $\cdots,$ $\lambda (n_r)$ の最小公倍数に等しい.
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$1$$2$$2$$4$$2$$6$$2$$6$$4$
$10$$10$$2$$12$$6$$4$$4$$16$$6$$18$$4$
$20$$6$$10$$22$$2$$20$$12$$18$$6$$28$$4$
$30$$30$$8$$10$$16$$12$$6$$36$$18$$12$$4$
$40$$40$$6$$42$$10$$12$$22$$46$$4$$42$$20$
$50$$16$$12$$52$$18$$20$$6$$18$$28$$58$$4$
$n$ 番目の完全数 (OEIS: A000396)
[定義]
完全数: 正の約数の和が自身の $2$ 倍に等しい正の整数.
[性質]
偶数の完全数は $2^{p-1}(2^p-1)$ ($p$: 素数) の形に表され, メルセンヌ素数 $2^p-1$ と $1$ 対 $1$ に対応する.
[注意]
下表において, 近似値の小数点以下は切り捨てである.
$n$$+1$$+2$$+3$$+4$$+5$
$0$$2^1\times$
$(2^2-1)$
$= 6$
$2^2\times$
$(2^3-1)$
$= 28$
$2^4\times$
$(2^5-1)$
$= 496$
$2^6\times$
$(2^7-1)$
$= 8128$
$2^{12}\times$
$(2^{13}-1)$
$= 33550336$
$5$$2^{16}\times$
$(2^{17}-1)$
$= 8589869056$
$2^{18}\times$
$(2^{19}-1)$
$\fallingdotseq\! 1\!\times\!10^{11}$
$2^{30}\times$
$(2^{31}-1)$
$\fallingdotseq\! 2\!\times\!10^{18}$
$2^{60}\times$
$(2^{61}-1)$
$\fallingdotseq\! 2\!\times\!10^{36}$
$2^{88}\times$
$(2^{89}-1)$
$\fallingdotseq\! 1\times\!10^{53}$
$10$$2^{106}\times$
$(2^{107}-1)$
$\fallingdotseq\! 1\!\times\!10^{64}$
$2^{126}\times$
$(2^{127}-1)$
$\fallingdotseq\! 1\!\times\!10^{76}$
$2^{520}\times$
$(2^{521}-1)$
$\fallingdotseq\! 2\!\times\!10^{313}$
$2^{606}\times$
$(2^{607}-1)$
$\fallingdotseq\! 1\!\times\!10^{365}$
$2^{1278}\times$
$(2^{1279}-1)$
$\fallingdotseq\! 5\!\times\!10^{769}$
$15$$2^{2202}\times$
$(2^{2203}-1)$
$\fallingdotseq\! 1\!\times\!10^{1326}$
$2^{2280}\times$
$(2^{2281}-1)$
$\fallingdotseq\! 9\!\times\!10^{1372}$
$2^{3216}\times$
$(2^{3217}-1)$
$\fallingdotseq\! 3\!\times\!10^{1936}$
$2^{4252}\times$
$(2^{4253}-1)$
$\fallingdotseq\! 1\!\times\!10^{2560}$
$2^{4422}\times$
$(2^{4423}-1)$
$\fallingdotseq\! 4\!\times\!10^{2662}$
$20$$2^{9688}\times$
$(2^{9689}-1)$
$\fallingdotseq\! 1\!\times\!10^{5833}$
$2^{9940}\times$
$(2^{9941}-1)$
$\fallingdotseq\! 5\!\times\!10^{5984}$
$2^{11212}\times$
$(2^{11213}-1)$
$\fallingdotseq\! 3\!\times\!10^{6750}$
$2^{19936}\times$
$(2^{19937}-1)$
$\fallingdotseq\! 9\!\times\!10^{12002}$
$2^{21700}\times$
$(2^{21701}-1)$
$\fallingdotseq\! 1\!\times\!10^{13065}$
$25$$2^{23208}\times$
$(2^{23209}-1)$
$\fallingdotseq\! 8\!\times\!10^{13972}$
$2^{44496}\times$
$(2^{44497}-1)$
$\fallingdotseq\! 3\!\times\!10^{26789}$
$2^{86242}\times$
$(2^{86243}-1)$
$\fallingdotseq\! 1\!\times\!10^{51923}$
$2^{110502}\times$
$(2^{110503}-1)$
$\fallingdotseq\! 1\!\times\!10^{66529}$
$2^{132048}\times$
$(2^{132049}-1)$
$\fallingdotseq\! 1\!\times\!10^{79501}$
$30$$2^{216090}\times$
$(2^{216091}-1)$
$\fallingdotseq\! 2\!\times\!10^{130099}$
$2^{756838}\times$
$(2^{756839}-1)$
$\fallingdotseq\! 1\!\times\!10^{455662}$
$2^{859432}\times$
$(2^{859433}-1)$
$\fallingdotseq\! 8\!\times\!10^{517429}$
$2^{1257786}\times$
$(2^{1257787}-1)$
$\fallingdotseq\! 8\!\times\!10^{757262}$
$2^{1398268}\times$
$(2^{1398269}-1)$
$\fallingdotseq\! 3\!\times\!10^{841841}$
$35$$2^{2976220}\times$
$(2^{2976221}-1)$
$\fallingdotseq\! 1\!\times\!10^{1791863}$
$2^{3021376}\times$
$(2^{3021377}-1)$
$\fallingdotseq\! 8\!\times\!10^{1819049}$
$2^{6972592}\times$
$(2^{6972593}-1)$
$\fallingdotseq\! 9\!\times\!10^{4197918}$
$2^{13466916}\times$
$(2^{13466917}-1)$
$\fallingdotseq\! 4\!\times\!10^{8107891}$
$2^{20996010}\times$
$(2^{20996011}-1)$
$\fallingdotseq\! 7\!\times\!10^{12640857}$
$40$$2^{24036582}\times$
$(2^{24036583}-1)$
$\fallingdotseq\! 4\!\times\!10^{14471464}$
$2^{25964950}\times$
$(2^{25964951}-1)$
$\fallingdotseq\! 7\!\times\!10^{15632457}$
$2^{30402456}\times$
$(2^{30402457}-1)$
$\fallingdotseq\! 4\!\times\!10^{18304102}$
$2^{32582656}\times$
$(2^{32582657}-1)$
$\fallingdotseq\! 7\!\times\!10^{19616713}$
$2^{37156666}\times$
$(2^{37156667}-1)$
$\fallingdotseq\! 2\!\times\!10^{22370542}$
$45$$2^{42643800}\times$
$(2^{42643801}-1)$
$\fallingdotseq\! 1\!\times\!10^{25674126}$
$2^{43112608}\times$
$(2^{43112609}-1)$
$\fallingdotseq\! 5\!\times\!10^{25956376}$
$2^{57885160}\times$
$(2^{57885161}-1)$
$\fallingdotseq\! 1\!\times\!10^{34850339}$
$?$$?$
$n$ 番目の調和数 $a_n,$ そのすべての正の約数の調和平均 $h_n$ (OEIS: A001599, A001600)
[定義]
調和数: すべての正の約数の調和平均が整数である正の整数.
$n$$1$$2$$3$$4$$5$
$a_n$$1$$6$$28$$140$$270$
$h_n$$1$$2$$3$$5$$6$
$n$$6$$7$$8$$9$$10$
$a_n$$496$$672$$1638$$2970$$6200$
$h_n$$5$$8$$9$$11$$10$
$n$$11$$12$$13$$14$$15$
$a_n$$8128$$8190$$18600$$18620$$27846$
$h_n$$7$$15$$15$$14$$17$
$n$$16$$17$$18$$19$$20$
$a_n$$30240$$32760$$55860$$105664$$117800$
$h_n$$24$$24$$21$$13$$19$
$n$ 番目の友愛数 $(a_n,b_n)$ $(a_n < b_n)$ (OEIS: A002025, A002046)
[定義]
友愛数: 正の整数 $a,$ $b$ の組で, $a,$ $b$ の正の約数の総和がともに $a+b$ に等しいもの.
$n$$1$$2$$3$$4$$5$
$a_n$$220$$1184$$2620$$5020$$6232$
$b_n$$284$$1210$$2924$$5564$$6368$
$n$$6$$7$$8$$9$$10$
$a_n$$10744$$12285$$17296$$63020$$66928$
$b_n$$10856$$14595$$18416$$76084$$66992$
$n$$11$$12$$13$$14$$15$
$a_n$$67095$$69615$$79750$$100485$$122265$
$b_n$$71145$$87633$$88730$$124155$$139815$
$n$$16$$17$$18$$19$$20$
$a_n$$122368$$141664$$142310$$171856$$176272$
$b_n$$123152$$153176$$168730$$176336$$180848$
$n$ 番目の婚約数 $(a_n,b_n)$ $(a_n < b_n)$ (OEIS: A003502, A003503)
[定義]
婚約数: 正の整数 $a,$ $b$ の組で, $a,$ $b$ の正の約数の総和がともに $a+b+1$ に等しいもの.
$n$$1$$2$$3$$4$$5$
$a_n$$48$$140$$1050$$1575$$2024$
$b_n$$75$$195$$1925$$1648$$2295$
$n$$6$$7$$8$$9$$10$
$a_n$$5775$$8892$$9504$$62744$$186615$
$b_n$$6128$$16587$$20735$$75495$$206504$
$n$$11$$12$$13$$14$$15$
$a_n$$196664$$199760$$266000$$312620$$526575$
$b_n$$219975$$309135$$507759$$549219$$544784$
$n$$16$$17$$18$$19$$20$
$a_n$$573560$$587460$$1000824$$1081184$$1139144$
$b_n$$817479$$1057595$$1902215$$1331967$$1159095$

合成数

$n$ 番目の高度合成数 $c_n,$ その正の約数の個数 $d(c_n)$ (OEIS: A000005, A002183)
[定義]
高度合成数: それ未満のどの正の整数よりも約数が多い正の整数.
$n$$1$$2$$3$$4$$5$
$c_n$$1$$2$
$= 2^1$
$4$
$= 2^2$
$6$
$= 2^13^1$
$12$
$= 2^2 3^1$
$d(c_n)$$1$$2$$3$$4$$6$
$n$$6$$7$$8$$9$$10$
$c_n$$24$
$= 2^3 3^1$
$36$
$= 2^2 3^2$
$48$
$= 2^4 3^1$
$60$
$= 2^2 3^1 5^1$
$120$
$= 2^3 3^1 5^1$
$d(c_n)$$8$$9$$10$$12$$16$
$n$$11$$12$$13$$14$$15$
$c_n$$180$
$= 2^2 3^2 5^1$
$240$
$= 2^4 3^1 5^1$
$360$
$= 2^3 3^2 5^1$
$720$
$= 2^4 3^2 5^1$
$840$
$= 2^3 3^1 5^1 7^1$
$d(c_n)$$18$$20$$24$$30$$32$
$n$$16$$17$$18$$19$$20$
$c_n$$1260$
$= 2^2 3^2 5^1 7^1$
$1680$
$= 2^4 3^1 5^1 7^1$
$2520$
$= 2^3 3^2 5^1 7^1$
$5040$
$= 2^4 3^2 5^1 7^1$
$7560$
$= 2^3 3^3 5^1 7^1$
$d(c_n)$$36$$40$$48$$60$$64$
カーマイケル数 (OEIS: A002997)
[定義]
フェルマー・テストを通過する (つまり任意の整数 $a$ に対して $a^q \equiv a \pmod q$ を満たす) 合成数 $q.$
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$561$$1105$$1729$$2465$$2821$$6601$$8911$$10585$$15841$$29341$
$10$$41041$$46657$$52633$$62745$$63973$$75361$$101101$$115921$$126217$$162401$

加法的整数論

分割数 $p(n)$ (OEIS: A000041)
[定義]
正の整数 $n$ を順序の違いを除いて正の整数の和として表す方法の総数.
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$2$$3$$5$$7$$11$$15$$22$$30$$42$
$10$$56$$77$$101$$135$$176$$231$$297$$385$$490$$627$
$20$$792$$1002$$1255$$1575$$1958$$2436$$3010$$3718$$4565$$5604$
$30$$6842$$8349$$10143$$12310$$14883$$17977$$21637$$26015$$31185$$37338$
$40$$44583$$53174$$63261$$75175$$89134$$105558$$124754$$147273$$173525$$204226$
$50$$239943$$281589$$329931$$386155$$451276$$526823$$614154$$715220$$831820$$966467$
整数の分割における項の総数 (OEIS: A006128)
[定義]
正の整数 $n$ を順序の違いを除いて正の整数の和として表す方法すべてにおける項の総数.
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$3$$6$$12$$20$$35$$54$$86$$128$$192$
$10$$275$$399$$556$$780$$1068$$1463$$1965$$2644$$3498$$4630$
$20$$6052$$7899$$10206$$13174$$16851$$21522$$27294$$34545$$43453$$54563$
$30$$68135$$84927$$105366$$130462$$160876$$198014$$242812$$297201$$362587$$441546$
ウェアリングの問題の解 $g(n)$ (OEIS: A002804)
[定義]
$g(n)$: すべての正の整数が $r$ 個の $n$ 乗数の和として表せるとしたときの $r$ の最小値.
[予想]
$g(n) = 2^n+\lfloor 1.5^n\rfloor -2$ ($n \leqq 471600000$ で確認済, Kubina & Wunderlich, $1990$).
$n$$+1$$+2$$+3$$+4$$+5$
$0$$1$$4$$9$$19$$37$
$5$$73$$143$$279$$548$$1079$
$10$$2132$$4223$$8384$$16673$$33203$
$15$$66190$$132055$$263619$$526502$$1051899$
$20$$2102137$$4201783$$8399828$$16794048$$33579681$
$25$$67146738$$134274541$$268520676$$536998744$$1073933573$
$30$$2147771272$$4295398733$$8590581749$$17180839921$$34361194475$
$35$$68721660898$$137442229716$$274882821311$$549763185440$$\:\!\!1099522685106\:\!\!$
$2$ 個の $0$ でない平方数の和 (OEIS: A000404)
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$2$$5$$8$$10$$13$$17$$18$$20$$25$$26$
$10$$29$$32$$34$$37$$40$$41$$45$$50$$52$$53$
$20$$58$$61$$65$$68$$72$$73$$74$$80$$82$$85$
$30$$89$$90$$97$$98$$100$$101$$104$$106$$109$$113$
$40$$116$$117$$122$$125$$128$$130$$136$$137$$145$$146$
$50$$148$$149$$153$$157$$160$$162$$164$$169$$170$$173$
$3$ 個の $0$ でない平方数の和 (OEIS: A000408)
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$3$$6$$9$$11$$12$$14$$17$$18$$19$$21$
$10$$22$$24$$26$$27$$29$$30$$33$$34$$35$$36$
$20$$38$$41$$42$$43$$44$$45$$46$$48$$49$$50$
$30$$51$$53$$54$$56$$57$$59$$61$$62$$65$$66$
$40$$67$$68$$69$$70$$72$$73$$74$$75$$76$$77$
$50$$78$$81$$82$$83$$84$$86$$88$$89$$90$$91$
$4$ 個の $0$ でない平方数の和 (OEIS: A000414)
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$4$$7$$10$$12$$13$$15$$16$$18$$19$$20$
$10$$21$$22$$23$$25$$26$$27$$28$$30$$31$$33$
$20$$34$$35$$36$$37$$38$$39$$40$$42$$43$$44$
$30$$45$$46$$47$$48$$49$$50$$51$$52$$53$$54$
$40$$55$$57$$58$$59$$60$$61$$62$$63$$64$$65$
$50$$66$$67$$68$$69$$70$$71$$72$$73$$74$$75$
$2$ 個の $0$ でない平方数の和としてちょうど $n$ 通りに表せる最小の整数 (OEIS: A016032)
$n$$+1$$+2$$+3$$+4$$+5$
$0$$2$$50$$325$$1105$$8125$
$5$$5525$$105625$$27625$$71825$$138125$
$10$$5281250$$160225$$1221025$$2442050$$1795625$
$15$$801125$$446265625$$2082925$$41259765625$$4005625$
$3$ 個の $0$ でない平方数の和としてちょうど $n$ 通りに表せる最小の整数 (OEIS: A025414)
$n$$+1$$+2$$+3$$+4$$+5$
$0$$3$$27$$54$$129$$194$
$5$$209$$341$$374$$614$$594$
$10$$854$$1106$$1314$$1154$$1286$
$15$$1746$$1634$$1881$$2141$$2246$
$4$ 個の $0$ でない平方数の和としてちょうど $n$ 通りに表せる最小の整数 (OEIS: A025416)
$n$$+1$$+2$$+3$$+4$$+5$
$0$$4$$31$$28$$52$$82$
$5$$90$$135$$130$$162$$198$
$10$$202$$252$$234$$210$$346$
$15$$306$$322$$423$$370$$330$
$n$ 番目のルース=アーロン・ペア $(a_n,a_n+1)$ (OEIS: A039752)
[定義]
ルース=アーロン・ぺア: 素因数の和が互いに等しい連続する $2$ 個の正の整数の組.
$n$$1$$2$$3$$4$$5$$6$$7$$8$$9$$10$
$a_n$$5$$8$$15$$77$$125$$714$$948$$1330$$1520$$1862$
$a_n+1$$6$$9$$16$$78$$126$$715$$949$$1331$$1521$$1863$
$n$$11$$12$$13$$14$$15$$16$$17$$18$$19$$20$
$a_n$$2491$$3248$$4185$$4191$$5405$$5560$$5959$$6867$$8280$$8463$
$a_n+1$$2492$$3249$$4186$$4192$$5406$$5561$$5960$$6868$$8281$$8464$

フィボナッチ数列など

フィボナッチ数 $F_n$ (OEIS: A000045)
[定義]
$F_1 = F_2 = 1,$ $F_{n+2} = F_n+F_{n+1}.$ 
[公式]
$F_n = \dfrac{1}{\sqrt 5}\left\{\left(\dfrac{1+\sqrt 5}{2}\right) ^n-\left(\dfrac{1-\sqrt 5}{2}\right) ^n\right\}.$ 
$n$$+1$$+2$$+3$$+4$$+5$
$0$$1$$1$$2$$3$$5$
$5$$8$$13$$21$$34$$55$
$10$$89$$144$$233$$377$$610$
$15$$987$$1597$$2584$$4181$$6765$
$20$$10946$$17711$$28657$$46368$$75025$
$25$$121393$$196418$$317811$$514229$$832040$
$30$$1346269$$2178309$$3524578$$5702887$$9227465$
$35$$14930352$$24157817$$39088169$$63245986$$102334155$
リュカ数 $L_n$ (OEIS: A000032)
[定義]
$L_1 = 2,$ $L_2 = 1,$ $L_{n+2} = L_n+L_{n+1}.$ 
[公式]
$L_n = \left(\dfrac{1+\sqrt 5}{2}\right) ^n+\left(\dfrac{1-\sqrt 5}{2}\right) ^n.$ 
$n$$+1$$+2$$+3$$+4$$+5$
$0$$2$$1$$3$$4$$7$
$5$$11$$18$$29$$47$$76$
$10$$123$$199$$322$$521$$843$
$15$$1364$$2207$$3571$$5778$$9349$
$20$$24476$$39603$$64079$$103682$$167761$
$25$$271443$$439204$$710647$$1149851$$1860498$
$30$$3010349$$4870847$$7881196$$12752043$$20633239$
$35$$33385282$$54018521$$87403803$$141422324$$228826127$
トリボナッチ数 $T_n$ (OEIS: A000073)
[定義]
$T_1 = 0,$ $T_2 = T_3 = 1,$ $T_{n+3} = T_n+T_{n+1}+T_{n+2}.$ 
[公式]
$T_n = \dfrac{\alpha ^n}{(\alpha -\beta )(\alpha -\gamma )}+\dfrac{\beta ^n}{(\beta -\gamma )(\beta -\alpha )}+\dfrac{\gamma ^n}{(\gamma -\alpha )(\gamma -\beta )}$ 
($\alpha,$ $\beta,$ $\gamma$ は $x^3-x^2-x-1 = 0$ の解).
$n$$+1$$+2$$+3$$+4$$+5$
$0$$0$$1$$1$$2$$4$
$5$$7$$13$$24$$44$$81$
$10$$149$$274$$504$$927$$1705$
$15$$3136$$5768$$10609$$19513$$35890$
$20$$35890$$66012$$121415$$223317$$410744$
$25$$755476$$1389537$$2555757$$4700770$$8646064$
$30$$15902591$$29249425$$53798080$$98950096$$181997601$
$35$$334745777$$615693474$$1132436852$$2082876103$$3831006429$
パドヴァン数 $P_n$ (OEIS: A000931)
[定義]
$P_1 = P_2 = 1,$ $P_3 = 2,$ $P_{n+3} = P_n+P_{n+1}.$ 
[注意]
初期値を $P_1 = P_2 = 0,$ $P_3 = 1$ とする流儀もある.
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$1$$2$$2$$3$$4$$5$$7$$9$$12$
$10$$16$$21$$28$$37$$49$$65$$86$$114$$151$$200$
$20$$265$$351$$465$$616$$816$$1081$$1432$$1897$$2513$$3329$
$30$$4410$$5842$$7739$$10252$$13581$$17991$$23833$$31572$$41824$$55405$
ペラン数 $P_n$ (OEIS: A001608)
[定義]
$P_1 = 0,$ $P_2 = 2,$ $P_3 = 3,$ $P_{n+3} = P_n+P_{n+1}.$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$0$$2$$3$$2$$5$$5$$7$$10$$12$$17$
$10$$22$$29$$39$$51$$68$$90$$119$$158$$209$$277$
$20$$367$$486$$644$$853$$1130$$1497$$1983$$2627$$3480$$4610$
$30$$6107$$8090$$10717$$14197$$18807$$24914$$33004$$43721$$57918$$76725$
シルヴェスター数列の第 $n$ 項 $s_n$ (OEIS: A000058)
[定義]
$s_1 = 2,$ $s_{n+1} = s_n{}^2-s_n+1.$ 
[性質]
$s_{n+1} = s_1\cdots s_n+1.$ 
$n$$+1$$+2$$+3$$+4$$+5$
$0$$2$$3$$7$$43$$1807$
$5$$3263443$$1.0\cdots\times 10^{13}$$1.1\cdots\times 10^{26}$$1.2\cdots\times 10^{52}$$1.6\cdots\times 10^{104}$

組合せ論

階乗 $n!$ (OEIS: A000142)
[意味]
互いに区別できる $n$ 個のものの順列の総数.
[初期値, 漸化式]
$0! = 1,$ $(n+1)! = (n+1)\cdot n!.$ 
$n$$+1$$+2$$+3$$+4$$+5$
$0$$1$$2$$6$$24$$120$
$5$$720$$5040$$40320$$362880$$3628800$
$10$$39916800$$479001600$$6227020800$$87178291200$$1307674368000$
モンモール数 $!n$ (OEIS: A000166)
[意味]
互いに区別できる $n$ 個のものの順列を各々がもとと異なる位置に並べ替える方法の総数.
[初期値, 漸化式]
$!1 = 0,$ $!2 = 1,$ $!(n+2) = (n+1)\{ !n+!(n+1)\}.$ 
$n$$+1$$+2$$+3$$+4$$+5$
$0$$0$$1$$2$$9$$44$
$5$$265$$1854$$14833$$133496$$1334961$
$10$$1334961$$14684570$$176214841$$2290792932$$32071101049$
二項係数 $\dbinom{n}{r} = {}_n\mathrm C_r$ $(0 \leqq r \leqq n)$
[意味]
互いに区別できる $n$ 個のものから $r$ 個をとる組合せの総数.
[初期値, 漸化式]
$\dbinom{n}{0} = \dbinom{n}{n} = 1,$ $\dbinom{n+1}{r+1} = \dbinom{n}{r}+\dbinom{n}{r+1}.$ 
[公式]
$\dbinom{n}{r} = {}_n\mathrm C_r = \dfrac{n!}{r!(n-r)!}.$ 
$n\backslash r$$0$$1$$2$$3$$4$$5$$6$$7$$8$$9$
$0$$1$
$1$$1$$1$
$2$$1$$2$$1$
$3$$1$$3$$3$$1$
$4$$1$$4$$6$$4$$1$
$5$$1$$5$$10$$10$$5$$1$
$6$$1$$6$$15$$20$$15$$6$$1$
$7$$1$$7$$21$$35$$35$$21$$7$$1$
$8$$1$$8$$28$$56$$70$$56$$28$$8$$1$
$9$$1$$9$$36$$84$$126$$126$$84$$36$$9$$1$
カタラン数 $C_n$ (OEIS: A000108)
[意味]
互いに区別のできない $2n$ 個のものを A, B に $1$ 個ずつ配っていき, 両者が合計 $n$ 個ずつもつようにするとき, どの時点でも A の個数が B の個数を下回らないような場合の数.
[初期値, 漸化式]
$C_0 = 1,$ $C_{n+1} = \displaystyle\sum_{k = 0}^nC_kC_{n-k}.$ 
[公式]
$C_n = \dfrac{{}_{2n}\mathrm C_n}{n+1} = \dfrac{(2n)!}{(n+1)!n!}.$ 
$n$$+1$$+2$$+3$$+4$$+5$
$0$$1$$2$$5$$14$$42$
$5$$132$$429$$1430$$4862$$16796$
$10$$58786$$208012$$742900$$2674440$$9694845$
$15$$35357670$$129644790$$477638700$$1767263190$$6564120420$
モツキン数 $M_n$ (OEIS: A001006)
[意味]
円周上の相異なる $n$ 個の点を互いに交わらないような線分で結ぶ方法の総数.
[初期値, 漸化式]
$M_0 = M_1 = 1,$ $M_{n+2} = \displaystyle\frac{2n+5}{n+4}M_{n+1}+\frac{3n+3}{n+4}M_n.$ 
$n$$+1$$+2$$+3$$+4$$+5$
$0$$1$$2$$4$$9$$21$
$5$$51$$127$$323$$835$$2188$
$10$$5798$$15511$$41835$$113634$$310572$
$15$$853467$$2356779$$6536382$$18199284$$50852019$
第 $1$ 種スターリング数 $\begin{bmatrix} n \\ r \end{bmatrix}$ $(0 \leqq r \leqq n)$
[意味]
互いに区別できる $n$ 個のものを $r$ 個の組に分けて各組で $1$ つの円順列を作る方法の総数.
[初期値, 漸化式]
$\begin{bmatrix} n \\ n \end{bmatrix} = 1$ $(n \geqq 0),$ $\begin{bmatrix} n \\ 0 \end{bmatrix} = 0$ $(n > 0),$ $\begin{bmatrix} n+1 \\ r+1 \end{bmatrix} = \begin{bmatrix} n \\ r \end{bmatrix}+n\begin{bmatrix} n \\ r+1 \end{bmatrix}.$ 
$n\backslash r$$0$$1$$2$$3$$4$$5$$6$$7$$8$$9$
$0$$1$
$1$$0$$1$
$2$$0$$1$$1$
$3$$0$$2$$3$$1$
$4$$0$$6$$11$$6$$1$
$5$$0$$24$$50$$35$$10$$1$
$6$$0$$120$$274$$225$$85$$15$$1$
$7$$0$$720$$1764$$1624$$735$$175$$21$$1$
$8$$0$$5040$$13068$$13132$$6769$$1960$$322$$28$$1$
$9$$0$$40320$$109584$$118124$$67284$$22449$$4536$$546$$36$$1$
第 $2$ 種スターリング数 $\begin{Bmatrix} n \\ r \end{Bmatrix} = {}_n\mathrm S_r$ $(0 \leqq r \leqq n)$
[意味]
互いに区別できる $n$ 個のものを $r$ 個の組に分ける方法の総数.
[初期値, 漸化式]
$\begin{Bmatrix} n \\ n \end{Bmatrix} \!=\! 1$ $(n \!\geqq\! 0),$ $\begin{Bmatrix} n \\ 0 \end{Bmatrix} \!=\! 0$ $(n \!>\! 0),$ $\begin{Bmatrix} n\!+\!1 \\ r\!+\!1 \end{Bmatrix} \!=\! \begin{Bmatrix} n \\ r \end{Bmatrix}\!+\!(r\!+\!1)\begin{Bmatrix} n \\ r\!+\!1 \end{Bmatrix}.$ 
$n\backslash r$$0$$1$$2$$3$$4$$5$$6$$7$$8$$9$
$0$$1$
$1$$0$$1$
$2$$0$$1$$1$
$3$$0$$1$$3$$1$
$4$$0$$1$$7$$6$$1$
$5$$0$$1$$15$$25$$10$$1$
$6$$0$$1$$31$$90$$65$$15$$1$
$7$$0$$1$$63$$301$$350$$140$$21$$1$
$8$$0$$1$$127$$966$$1701$$1050$$266$$28$$1$
$9$$0$$1$$255$$3025$$7770$$6951$$2646$$462$$36$$1$
ベル数 $B_n$ (OEIS: A000110)
[意味]
$n$ 個のものをグループ分けする方法の総数.
[初期値, 漸化式]
$B_0 = 1,$ $B_{n+1} = \displaystyle\sum_{k = 0}^n\dbinom{n}{k}B_k.$ 
$n$$+1$$+2$$+3$$+4$$+5$
$0$$1$$2$$5$$15$$52$
$5$$203$$877$$4140$$21147$$115975$
$10$$678570$$4213597$$27644437$$190899322$$1382958545$
第 $1$ 次オイラー数 $\left\langle\!\!\!\begin{array}{c} n \\ r \end{array}\!\!\!\right\rangle$ $(0 \leqq r \leqq n-1)$
[意味]
$1,$ $\cdots,$ $n$ の順列で直前より大きい数が $r$ 個だけあるものの総数.
[初期値, 漸化式]
$\left\langle\!\!\!\begin{array}{c} n \\ 0 \end{array}\!\!\!\right\rangle = 1$ $(n \geqq 0),$ $\displaystyle\left\langle\!\!\!\begin{array}{c} n+1 \\ r+1 \end{array}\!\!\!\right\rangle = (n-r)\left\langle\!\!\!\begin{array}{c} n \\ r \end{array}\!\!\!\right\rangle +(r+2)\left\langle\!\!\!\begin{array}{c} n \\ r+1 \end{array}\!\!\!\right\rangle.$ 
[公式]
$\displaystyle\left\langle\!\!\!\begin{array}{c} n \\ r \end{array}\!\!\!\right\rangle = \sum_{i = 0}^r(-1)^i\binom{n+1}{i}(r+1-i)^n.$ 
$n\backslash r$$0$$1$$2$$3$$4$$5$$6$$7$$8$$9$
$0$$1$
$1$$1$
$2$$1$$1$
$3$$1$$4$$1$
$4$$1$$11$$11$$1$
$5$$1$$26$$66$$26$$1$
$6$$1$$57$$302$$302$$57$$1$
$7$$1$$120$$1191$$2416$$1191$$120$$1$
$8$$1$$247$$4293$$15619$$15619$$4293$$247$$1$
$9$$1$$502$$14608$$88234$$156190$$88234$$14608$$502$$1$
第 $2$ 次オイラー数 $\left\langle\!\!\!\left\langle\!\!\!\begin{array}{c} n \\ r \end{array}\!\!\!\right\rangle\!\!\!\right\rangle$ $(0 \leqq r \leqq n-1)$
[意味]
$1,$ $1,$ $\cdots,$ $n,$ $n$ の順列で直前より大きい数が $r$ 個だけあるものの総数.
[初期値, 漸化式]
$\left\langle\!\!\!\left\langle\!\!\!\begin{array}{c} n \\ 0 \end{array}\!\!\!\right\rangle\!\!\!\right\rangle = 1$ $(n \geqq 0),$ $\displaystyle\left\langle\!\!\!\left\langle\!\!\!\begin{array}{c} n+1 \\ r+1 \end{array}\!\!\!\right\rangle\!\!\!\right\rangle = (2n-r)\!\left\langle\!\!\!\left\langle\!\!\!\begin{array}{c} n \\ r \end{array}\!\!\!\right\rangle\!\!\!\right\rangle +(r+2)\!\left\langle\!\!\!\left\langle\!\!\!\begin{array}{c} n \\ r+1 \end{array}\!\!\!\right\rangle\!\!\!\right\rangle.$ 
$n\backslash r$$0$$1$$2$$3$$4$$5$$6$$7$$8$$9$
$0$$1$
$1$$1$
$2$$1$$2$
$3$$1$$8$$6$
$4$$1$$22$$58$$24$
$5$$1$$52$$328$$444$$120$
$6$$1$$114$$1452$$4400$$3708$$720$
$7$$1$$240$$5610$$32120$$58140$$33984$$5040$
$8$$1$$494$$19950$$195800$$644020$$785304$$341136$$40320$
$n$ 番目のベルヌーイ数 $B_n$ (OEIS: A027641, A027642)
[定義]
$\displaystyle\frac{x}{e^x-1} = \sum_{n = 0}^\infty\frac{B_n}{n!}x^n.$ 
[初期値, 漸化式]
$B_0 = 1,$ $B_{n+1} = -\displaystyle\frac{1}{n+2}\sum_{k = 0}^n\binom{n+2}{k}B_k.$ 
$n$$+1$$+2$$+3$$+4$$+5$
$0$$\dfrac{-1}{2}$$\dfrac{1}{6}$$0$$\dfrac{-1}{30}$$0$
$5$$\dfrac{1}{42}$$0$$\dfrac{-1}{30}$$0$$\dfrac{5}{66}$
$10$$0$$\dfrac{-691}{2730}$$0$$\dfrac{7}{6}$$0$
$15$$\dfrac{-3617}{510}$$0$$\dfrac{43867}{798}$$0$$\dfrac{-174611}{330}$
$20$$0$$\dfrac{854513}{138}$$0$$\dfrac{-236364091}{2730}$$0$
平面が $n$ 本の直線で分割されてできる領域の個数の最大値 $a_n$ (OEIS: A000124)
[公式]
$a_n = \dfrac{n^2+n+2}{2} = 1+\dfrac{n(n+1)}{2}.$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$2$$4$$7$$11$$16$$22$$29$$37$$46$$56$
$10$$67$$79$$92$$106$$121$$137$$154$$172$$191$$211$
平面が $n$ 個の円周で分割されてできる領域の個数の最大値 $a_n$ (OEIS: A014206)
[公式]
$a_n = n^2-n+2.$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$2$$4$$8$$14$$22$$32$$44$$58$$74$$92$
$10$$112$$134$$158$$184$$212$$242$$274$$308$$344$$382$
平面が $n$ 個の楕円の周で分割されてできる領域の個数の最大値 $a_n$ (OEIS: A051890)
[公式]
$a_n = 2(n^2-n+1).$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$2$$6$$14$$26$$42$$62$$86$$114$$146$$182$
$10$$222$$266$$314$$366$$422$$482$$546$$614$$686$$762$
平面が $n$ 個の三角形の周で分割されてできる領域の個数の最大値 $a_n$ (OEIS: A077588)
[公式]
$a_n = 3n^2-3n+2.$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$2$$8$$20$$38$$62$$92$$128$$170$$218$$272$
$10$$332$$398$$470$$548$$632$$722$$818$$920$$1028$$1142$
空間が $n$ 枚の平面で分割されてできる領域の個数の最大値 $a_n$ (OEIS: A000125)
[公式]
$a_n = \dfrac{1}{6}(n+1)(n^2-n+6).$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$2$$4$$8$$15$$26$$42$$64$$93$$130$$176$
$10$$232$$299$$378$$470$$576$$697$$834$$988$$1160$$1351$
空間が $n$ 個の球面で分割されてできる領域の個数の最大値 $a_n$ (OEIS: A046127)
[公式]
$a_n = \dfrac{1}{3}n(n^2-3n+8).$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$2$$4$$8$$16$$30$$52$$84$$128$$186$$260$
$10$$352$$464$$598$$756$$940$$1152$$1394$$1668$$1976$$2320$
モーザー数列の第 $n$ 項 $M_n$ (OEIS: A000127)
[定義]
円が周上の $n$ 個の点を結ぶ弦により分割されてできる領域の個数の最大値.
[公式]
$M_n = 1+\dfrac{1}{24}(n-1)n(n^2-5n+18) = \dfrac{1}{24}(n^4-6n^3+23n^2-18n+24).$ 
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$1$$2$$4$$8$$16$$31$$57$$99$$163$$256$
$10$$386$$562$$794$$1093$$1471$$1941$$2517$$3214$$4048$$5036$
長方形の長方形への分割による分割数の一般化 (OEIS: A360629)
[定義]
横, 縦の長さが整数 $m,$ $n$ である長方形に敷き詰められる辺の長さが整数である長方形の組合せの総数.
$m\backslash n$$1$$2$$3$$4$$5$$6$$7$$8$$9$$10$
$1$$1$
$2$$2$$4$
$3$$3$$10$$21$
$4$$5$$22$$73$$192$
$5$$7$$44$$190$$703$$2035$
$6$$11$$91$$510$$2287$$8581$$27407$
$7$$15$$172$$1196$$6738$$30209$$118461$$?$
$8$$22$$326$$2895$$?$$?$$?$$?$$?$
$9$$30$$595$$6437$$?$$?$$?$$?$$?$$?$
$10$$42$$1066$$14281$$?$$?$$?$$?$$?$$?$$?$

不定方程式の解

ピタゴラスの $3$ つ組など

原始的なピタゴラスの $3$ つ組 $(a,b,c),$ 対応するピタゴラスの三角形の面積 $S,$ 周の長さ $L$
[定義]
$a^2+b^2 = c^2$ を満たす互いに素な正の整数の組.
[公式]
$a,$ $b$ の偶奇は異なる. $a$ を奇数, $b$ を偶数とすると, $a,$ $b,$ $c$ は偶奇の異なる互いに素な整数 $m,$ $n$ $(m > n > 0)$ を用いて $(a,b,c) = (m^2-n^2,2mn,m^2+n^2)$ と表される.
[注意]
次の表で $a,$ $b,$ $c,$ $S,$ $L$ は, $c$ が小さい順, 次に $S$ が小さい順に並ぶ.
$m$$2$$3$$4$$4$$5$$6$$5$$7$$6$$8$
$n$$1$$2$$1$$3$$2$$1$$4$$2$$5$$1$
$a$$3$$5$$15$$7$$21$$35$$9$$45$$11$$63$
$b$$4$$12$$8$$24$$20$$12$$40$$28$$60$$16$
$c$$5$$13$$17$$25$$29$$37$$41$$53$$61$$65$
$S$$6$$30$$60$$84$$210$$210$$180$$630$$330$$504$
$L$$12$$30$$40$$56$$70$$84$$90$$126$$132$$144$
$m$$7$$8$$7$$9$$8$$9$$10$$10$$8$$11$
$n$$4$$3$$6$$2$$5$$4$$1$$3$$7$$2$
$a$$33$$55$$13$$77$$39$$65$$99$$91$$15$$117$
$b$$56$$48$$84$$36$$80$$72$$20$$60$$112$$44$
$c$$65$$73$$85$$85$$89$$97$$101$$109$$113$$125$
$S$$924$$1320$$546$$1386$$1560$$2340$$990$$2730$$840$$2574$
$L$$154$$176$$182$$198$$208$$234$$220$$260$$240$$286$
$m$$11$$9$$12$$10$$11$$12$$13$$10$$11$$13$
$n$$4$$8$$1$$7$$6$$5$$2$$9$$8$$4$
$a$$105$$17$$143$$51$$85$$119$$165$$19$$57$$153$
$b$$88$$144$$24$$140$$132$$120$$52$$180$$176$$104$
$c$$137$$145$$145$$149$$157$$169$$173$$181$$185$$185$
$S$$4620$$1224$$1716$$3570$$5610$$7140$$4290$$1710$$5016$$7956$
$L$$330$$306$$312$$340$$374$$408$$390$$380$$418$$442$
$m$$12$$14$$14$$13$$11$$14$$15$$13$$15$$16$
$n$$7$$1$$3$$6$$10$$5$$2$$8$$4$$1$
$a$$95$$195$$187$$133$$21$$171$$221$$105$$209$$255$
$b$$168$$28$$84$$156$$220$$140$$60$$208$$120$$32$
$c$$193$$197$$205$$205$$221$$221$$229$$233$$241$$257$
$S$$7980$$2730$$7854$$10374$$2310$$11970$$6630$$10920$$12540$$4080$
$L$$456$$420$$476$$494$$462$$532$$510$$546$$570$$544$
$m$$16$$12$$13$$14$$16$$15$$17$$16$$17$$13$
$n$$3$$11$$10$$9$$5$$8$$2$$7$$4$$12$
$a$$247$$23$$69$$115$$231$$161$$285$$207$$273$$25$
$b$$96$$264$$260$$252$$160$$240$$68$$224$$136$$312$
$c$$265$$265$$269$$277$$281$$289$$293$$305$$305$$313$
$S$$11856$$3036$$8970$$14490$$18480$$19320$$9690$$23184$$18564$$3900$
$L$$608$$552$$598$$644$$672$$690$$646$$736$$714$$650$
$m$$14$$17$$18$$16$$18$$17$$19$$14$$18$$19$
$n$$11$$6$$1$$9$$5$$8$$2$$13$$7$$4$
$a$$75$$253$$323$$175$$299$$225$$357$$27$$275$$345$
$b$$308$$204$$36$$288$$180$$272$$76$$364$$252$$152$
$c$$317$$325$$325$$337$$349$$353$$365$$365$$373$$377$
$S$$11550$$25806$$5814$$25200$$26910$$30600$$13566$$4914$$34650$$26220$
$L$$700$$782$$684$$800$$828$$850$$798$$756$$900$$874$
原始的なヘロンの三角形の $3$ 辺の長さ $a,$ $b,$ $c,$ 面積 $S,$ 周の長さ $L$
[定義]
ヘロンの三角形: $3$ 辺の長さ, 面積が整数である三角形.
そのうち, $3$ 辺の長さが互いに素なものは原始的であるという.
[公式]
任意のヘロンの三角形の $3$ 辺の長さ $(a,b,c)$ $(a \geqq b \geqq c)$ の比は, $mn > h^2 \geqq \dfrac{m^2n}{2m+n},$ $m \geqq n$ なる互いに素な正の整数 $m,$ $n,$ $h$ を用いて $a:b:c = n(m^2+h^2):m(n^2+h^2):(m+n)(mn-h^2)$ で表される.
[注意]
次の表で $S,$ $L,$ $a,$ $b,$ $c$ は, $S$ が小さい順, $L$ が小さい順, $a$ が小さい順に並ぶ. $n(m^2+h^2),$ $m(n^2+h^2),$ $(m+n)(mn-h^2)$ の最大公約数 $g$ の値を付記した.
$m$$2$$6$$12$$6$$3$$8$$6$$6$$3$$5$
$n$$1$$4$$3$$2$$2$$1$$3$$1$$3$$3$
$h$$1$$3$$4$$3$$2$$2$$4$$2$$2$$3$
$g$$1$$30$$60$$6$$2$$4$$6$$2$$3$$6$
$S$$6$$12$$12$$24$$30$$36$$36$$42$$60$$60$
$L$$12$$16$$18$$32$$30$$36$$54$$42$$36$$40$
$a$$5$$6$$8$$15$$13$$17$$26$$20$$13$$17$
$b$$4$$5$$5$$13$$12$$10$$25$$15$$13$$15$
$c$$3$$5$$5$$4$$5$$9$$3$$7$$10$$8$
$m$$60$$5$$9$$12$$7$$14$$4$$21$$15$$9$
$n$$5$$1$$2$$8$$6$$6$$3$$3$$3$$3$
$h$$12$$2$$3$$9$$4$$7$$3$$7$$5$$5$
$g$$780$$1$$9$$60$$26$$70$$3$$42$$30$$6$
$S$$60$$60$$66$$72$$84$$84$$84$$84$$90$$90$
$L$$50$$60$$44$$64$$42$$48$$56$$72$$54$$108$
$a$$24$$29$$20$$30$$15$$21$$25$$35$$25$$53$
$b$$13$$25$$13$$29$$14$$17$$24$$29$$17$$51$
$c$$13$$6$$11$$5$$13$$10$$7$$8$$12$$4$
$m$$18$$5$$60$$15$$21$$14$$9$$8$$13$$12$
$n$$1$$5$$8$$1$$18$$1$$6$$3$$2$$1$
$h$$3$$3$$15$$3$$14$$3$$7$$4$$4$$3$
$g$$9$$10$$1020$$6$$546$$5$$15$$8$$10$$3$
$S$$114$$120$$120$$120$$126$$126$$126$$132$$156$$156$
$L$$76$$50$$64$$80$$54$$84$$108$$66$$78$$104$
$a$$37$$17$$30$$39$$21$$41$$52$$30$$37$$51$
$b$$20$$17$$17$$25$$20$$28$$51$$25$$26$$40$
$c$$19$$16$$17$$16$$13$$15$$5$$11$$15$$13$
$m$$4$$7$$168$$20$$5$$11$$9$$10$$7$$7$
$n$$4$$3$$7$$6$$4$$1$$8$$7$$3$$5$
$h$$3$$4$$24$$9$$4$$3$$6$$6$$3$$5$
$g$$4$$5$$4200$$78$$4$$2$$36$$34$$6$$10$
$S$$168$$168$$168$$180$$180$$198$$204$$210$$210$$210$
$L$$64$$84$$98$$80$$90$$132$$68$$70$$70$$84$
$a$$25$$39$$48$$37$$41$$65$$26$$28$$29$$37$
$b$$25$$35$$25$$30$$40$$55$$25$$25$$21$$35$
$c$$14$$10$$25$$13$$9$$12$$17$$17$$20$$12$
$m$$14$$5$$10$$24$$39$$24$$8$$63$$14$$22$
$n$$3$$2$$5$$3$$6$$15$$7$$28$$4$$8$
$h$$5$$3$$7$$8$$13$$16$$6$$36$$7$$11$
$g$$17$$1$$5$$24$$195$$312$$20$$3276$$14$$110$
$S$$210$$210$$210$$216$$234$$240$$252$$252$$252$$264$
$L$$84$$140$$300$$162$$108$$90$$84$$98$$144$$96$
$a$$39$$68$$149$$80$$52$$40$$35$$45$$70$$44$
$b$$28$$65$$148$$73$$41$$37$$34$$40$$65$$37$
$c$$17$$7$$3$$9$$15$$13$$15$$13$$9$$15$
$m$$32$$25$$144$$24$$15$$51$$55$$22$$6$$10$
$n$$1$$2$$9$$1$$10$$9$$30$$3$$5$$1$
$h$$4$$5$$32$$4$$12$$17$$33$$6$$5$$3$
$g$$16$$25$$2448$$8$$30$$510$$2805$$30$$5$$1$
$S$$264$$270$$288$$300$$300$$306$$330$$330$$330$$330$
$L$$132$$108$$162$$150$$250$$108$$100$$110$$132$$220$
$a$$65$$52$$80$$74$$123$$51$$44$$52$$61$$109$
$b$$34$$29$$65$$51$$122$$37$$39$$33$$60$$100$
$c$$33$$27$$17$$25$$5$$20$$17$$25$$11$$11$
原始的なピタゴラスの $4$ つ組 $(a,b,c,d),$ 対応する直角三角錐の体積 $V$
[定義]
$a^2+b^2+c^2 = d^2$ を満たす互いに素な正の整数の組.
[公式]
$a,$ $b,$ $c$ のうち $2$ つは偶数, $1$ つは奇数である. $a$ を奇数, $b,$ $c$ を偶数とすると, $a,$ $b,$ $c,$ $d$ は非負整数 $k,$ $l,$ $m,$ $n$ ($k,$ $l,$ $m,$ $n$ が満たすべき条件については省略) を用いて $(a,b,c,d) = (k^2+l^2-m^2-n^2,2(km-ln),2(kn+lm),k^2+l^2+m^2+n^2)$ と表される.
[注意]
次の表で $a,$ $b,$ $c,$ $d$ は, $d$ が小さい順, 次に $V$ が小さい順に並ぶ.
$k$$1$$2$$2$$2$$3$$3$$2$$3$$3$$3$
$l$$1$$1$$1$$2$$1$$0$$2$$1$$2$$0$
$m$$1$$1$$2$$1$$1$$1$$2$$1$$1$$2$
$n$$0$$1$$0$$0$$0$$1$$1$$2$$1$$2$
$a$$1$$3$$1$$7$$9$$7$$3$$5$$11$$1$
$b$$2$$2$$8$$4$$6$$6$$4$$2$$2$$12$
$c$$2$$6$$4$$4$$2$$6$$12$$14$$10$$12$
$d$$3$$7$$9$$9$$11$$11$$13$$15$$15$$17$
$V$$4/3$$12$$32/3$$112/3$$36$$84$$48$$140/3$$220/3$$48$
$k$$3$$3$$3$$4$$3$$4$$4$$4$$2$$3$
$l$$2$$1$$3$$1$$2$$2$$1$$0$$3$$2$
$m$$2$$3$$1$$1$$2$$1$$2$$2$$3$$3$
$n$$0$$0$$0$$1$$2$$0$$0$$1$$1$$1$
$a$$9$$1$$17$$15$$5$$19$$13$$11$$3$$3$
$b$$12$$18$$6$$6$$4$$8$$16$$16$$6$$14$
$c$$8$$6$$6$$10$$20$$4$$4$$8$$22$$18$
$d$$17$$19$$19$$19$$21$$21$$21$$21$$23$$23$
$V$$288$$36$$204$$300$$400/3$$608/3$$832/3$$1408/3$$132$$252$

ペル方程式

実 $2$ 次体 $\mathbb Q(\sqrt d)$ の基本単数 $a+b\sqrt d$ ($a,$ $b$: 正の整数または半整数),
$|x^2-dy^2| = 1$ の最小の正の整数解 $(x,y) = (x_1,y_1),$
$\eta = a+b\sqrt d,$ $\varepsilon = x_1+y_1\sqrt d$ のノルム $N(\eta ) = N(\varepsilon )$
[性質]
$|x^2-dy^2| = 1$ の任意の正の整数解 $(x,y)$ はある正の整数 $n$ に対して $x+y\sqrt d = \varepsilon ^n$ を満たす.
$\varepsilon \neq \eta$ のとき $\varepsilon = \eta ^3$ ($d \equiv 2,$ $3$ $(\text{mod}\ 4)$ のとき $\varepsilon = \eta$).
$d$$2$$3$$5$$6$$7$
$a$$1$$2$$1/2$$5$$8$
$b$$1$$1$$1/2$$2$$3$
$x_1$$1$$2$$2$$5$$8$
$y_1$$1$$1$$1$$2$$3$
$N(\eta ) \!=\! N(\varepsilon )$$-1$$1$$-1$$1$$1$
$d$$10$$11$$13$$14$$15$
$a$$3$$10$$3/2$$15$$4$
$b$$1$$3$$1/2$$4$$1$
$x_1$$3$$10$$18$$15$$4$
$y_1$$1$$3$$5$$4$$1$
$N(\eta ) \!=\! N(\varepsilon )$$-1$$1$$-1$$1$$1$
$d$$17$$19$$21$$22$$23$
$a$$4$$170$$5/2$$197$$24$
$b$$1$$39$$1/2$$42$$5$
$x_1$$4$$170$$55$$197$$24$
$y_1$$1$$39$$12$$42$$5$
$N(\eta ) \!=\! N(\varepsilon )$$-1$$1$$1$$1$$1$
$d$$26$$29$$30$$31$$33$
$a$$5$$5/2$$11$$1520$$23$
$b$$1$$1/2$$2$$273$$4$
$x_1$$5$$70$$11$$1520$$23$
$y_1$$1$$13$$2$$273$$4$
$N(\eta ) \!=\! N(\varepsilon )$$-1$$-1$$1$$1$$1$
$d$$34$$35$$37$$38$$39$
$a$$35$$6$$6$$37$$25$
$b$$6$$1$$1$$6$$4$
$x_1$$35$$6$$6$$37$$25$
$y_1$$6$$1$$1$$6$$4$
$N(\eta ) \!=\! N(\varepsilon )$$-1$$1$$-1$$1$$1$
$d$$41$$42$$43$$46$$47$
$a$$32$$13$$3482$$24335$$48$
$b$$5$$2$$531$$3588$$7$
$x_1$$32$$13$$3482$$24335$$48$
$y_1$$5$$2$$531$$3588$$7$
$N(\eta ) \!=\! N(\varepsilon )$$-1$$1$$1$$1$$1$
$d$$51$$53$$55$$57$$58$
$a$$50$$7/2$$89$$151$$99$
$b$$7$$1/2$$12$$20$$13$
$x_1$$50$$182$$89$$151$$99$
$y_1$$7$$25$$12$$20$$13$
$N(\eta ) \!=\! N(\varepsilon )$$1$$-1$$1$$1$$-1$
$d$$59$$61$$62$$65$$66$
$a$$530$$39/2$$63$$8$$65$
$b$$69$$5/2$$8$$1$$8$
$x_1$$530$$29718$$63$$8$$65$
$y_1$$69$$3805$$8$$1$$8$
$N(\eta ) \!=\! N(\varepsilon )$$1$$-1$$1$$-1$$1$
$d$$67$$69$$70$$71$$73$
$a$$48842$$25/2$$251$$3480$$1068$
$b$$5967$$3/2$$30$$413$$125$
$x_1$$48842$$7775$$251$$3480$$1068$
$y_1$$5967$$936$$30$$413$$125$
$N(\eta ) \!=\! N(\varepsilon )$$1$$1$$1$$1$$-1$
$d$$74$$77$$78$$79$$82$
$a$$43$$9/2$$53$$80$$9$
$b$$5$$1/2$$6$$9$$1$
$x_1$$43$$351$$53$$80$$9$
$y_1$$5$$40$$6$$9$$1$
$N(\eta ) \!=\! N(\varepsilon )$$-1$$1$$1$$1$$-1$
$d$$83$$85$$86$$87$$89$
$a$$82$$9/2$$10405$$28$$500$
$b$$9$$1/2$$1122$$3$$53$
$x_1$$82$$378$$10405$$28$$500$
$y_1$$9$$41$$1122$$3$$53$
$N(\eta ) \!=\! N(\varepsilon )$$1$$-1$$1$$1$$-1$
$d$$91$$93$$94$$95$$97$
$a$$1574$$29/2$$2143295$$39$$5604$
$b$$165$$3/2$$221064$$4$$569$
$x_1$$1574$$12151$$2143295$$39$$5604$
$y_1$$165$$1260$$221064$$4$$569$
$N(\eta ) \!=\! N(\varepsilon )$$1$$1$$1$$1$$-1$
$x^2-dy^2 = -1$ が有理数解をもつような平方因数をもたない整数 $d\,(> 1)$ (OEIS: A020893)
[性質]
$d$ は, $4$ を法として $3$ と合同な素因数をもたない, $2$ 個の平方数の和として表される.
[注意]
この表において, $d = 34$ の場合を除いて, $x^2-dy^2 = -1$ は整数解をもつ.
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$2$$5$$10$$13$$17$$26$$29$$34$$37$$41$
$10$$53$$58$$61$$65$$73$$74$$82$$85$$89$$97$
$|x^2-2y^2| = 1$ の $n$ 番目の正の整数解 $(x,y) = (x_n,y_n)$
[意味]
$x_n$: $\sqrt 2$ の近似分数の分子, 半ペル=リュカ数 (OEIS: A001333).
[初期値, 漸化式]
$x_1 = 1,$ $x_2 = 3,$ $x_{n+2} = x_n+2x_{n+1}.$ 
[公式]
$x_n = \dfrac{(1+\sqrt 2)^n+(1-\sqrt 2)^n}{2}.$ 
[意味]
$y_n$: $\sqrt 2$ の近似分数の分母, ペル数 (OEIS: A000129).
[初期値, 漸化式]
$y_1 = 1,$ $y_2 = 2,$ $y_{n+2} = y_n+2y_{n+1}.$ 
[公式]
$y_n = \dfrac{(1+\sqrt 2)^n-(1-\sqrt 2)^n}{2\sqrt 2}.$ 
[性質]
$x_n{}^2-2y_n{}^2 = (-1)^n.$ 
$n$$1$$2$$3$$4$$5$$6$$7$$8$$9$$10$
$x_n$$1$$3$$7$$17$$41$$99$$239$$577$$1393$$3363$
$y_n$$1$$2$$5$$12$$29$$70$$169$$408$$985$$2378$
$x^2-3y^2 = 1$ の $n$ 番目の正の整数解 $(x,y) = (x_n,y_n)$
[意味]
$x_n$: $\sqrt 3$ の近似分数の分子 (OEIS: A001075).
[初期値, 漸化式]
$x_1 = 2,$ $x_2 = 7,$ $x_{n+2} = 4x_{n+1}-x_n.$ 
[公式]
$x_n = \dfrac{(2+\sqrt 3)^n+(2-\sqrt 3)^n}{2}.$ 
[意味]
$y_n$: $\sqrt 3$ の近似分数の分母 (OEIS: A001353).
[初期値, 漸化式]
$y_1 = 1,$ $y_2 = 4,$ $y_{n+2} = 4y_{n+1}-y_n.$ 
[公式]
$y_n = \dfrac{(2+\sqrt 3)^n-(2-\sqrt 3)^n}{2\sqrt 3}.$ 
$n$$1$$2$$3$$4$$5$$6$$7$$8$$9$$10$
$x_n$$2$$7$$26$$97$$362$$1351$$5042$$18817$$70226$$262087$
$y_n$$1$$4$$15$$56$$209$$780$$2911$$10864$$40545$$151316$
$|x^2-5y^2| = 1$ の $n$ 番目の正の整数解 $(x,y) = (x_n,y_n)$
[意味]
$x_n$: $\sqrt 5$ の近似分数の分子 (OEIS: A001077).
[初期値, 漸化式]
$x_1 = 2,$ $x_2 = 9,$ $x_{n+2} = x_n+4x_{n+1}.$ 
[公式]
$x_n = \dfrac{(2+\sqrt 5)^n+(2-\sqrt 5)^n}{2}.$ 
[意味]
$y_n$: $\sqrt 5$ の近似分数の分母 (OEIS: A001076).
[初期値, 漸化式]
$y_1 = 1,$ $y_2 = 4,$ $y_{n+2} = y_n+4y_{n+1}.$ 
[公式]
$y_n = \dfrac{(2+\sqrt 5)^n-(2-\sqrt 5)^n}{2\sqrt 5}.$ 
[性質]
$x_n{}^2-5y_n{}^2 = (-1)^n.$ 
$n$$1$$2$$3$$4$$5$$6$$7$$8$$9$$10$
$x_n$$2$$9$$38$$161$$682$$2889$$12238$$51841$$219602$$930249$
$y_n$$1$$4$$17$$72$$305$$1292$$5473$$23184$$98209$$416020$

その他

$n$ 番目の平方因数をもたない合同数 $q_n$ (OEIS: A006991)
[定義]
合同数: 辺の長さがすべて有理数である直角三角形の面積となるような正の整数,
つまり $a^2+b^2 = c^2,$ $\dfrac{ab}{2} = q$ が有理数解 $(a,b,c)$ をもつような正の整数 $q.$
$n$$+1$$+2$$+3$$+4$$+5$$+6$$+7$$+8$$+9$$+10$
$0$$5$$6$$7$$13$$14$$15$$21$$22$$23$$29$
$10$$30$$31$$34$$37$$38$$39$$41$$46$$47$$53$
$20$$55$$61$$62$$65$$69$$70$$71$$77$$78$$79$
$30$$85$$86$$87$$93$$94$$95$$101$$102$$103$$109$
$40$$110$$111$$118$$119$$127$$133$$134$$137$$138$$141$
$50$$142$$143$$145$$149$$151$$154$$157$$158$$159$$161$
$n$ 番目のマルコフ数 $z_n$ (OEIS: A002559),
マルコフの $3$ つ組 $(x_n,y_n,z_n)$ $(x_n \leqq y_n \leqq z_n)$
[定義]
マルコフ数: $x^2+y^2+z^2 = 3xyz$ の正の整数解に現れる整数.
マルコフの $3$ つ組: $x^2+y^2+z^2 = 3xyz,$ $0 < x \leqq y \leqq z$ の整数解 $(x,y,z).$
$n$$1$$2$$3$$4$$5$$6$$7$$8$$9$$10$
$x_n$$1$$1$$1$$1$$2$$1$$1$$2$$5$$1$
$y_n$$1$$1$$2$$5$$5$$13$$34$$29$$13$$89$
$z_n$$1$$2$$5$$13$$29$$34$$89$$169$$194$$233$
$n$$11$$12$$13$$14$$15$$16$$17$$18$$19$$20$
$x_n$$5$$1$$2$$13$$1$$5$$1$$2$$5$$13$
$y_n$$29$$233$$169$$34$$610$$194$$1597$$985$$433$$194$
$z_n$$433$$610$$985$$1325$$1597$$2897$$4181$$5741$$6466$ $7561$
$n$$21$$22$$23$$24$$25$$26$$27$$28$$29$$30$
$x_n$$34$$1$$29$$1$$2$$29$$5$$13$$89$$1$
$y_n$$89$$4181$$169$$10946$$5741$$433$$2897$$1325$$233$$28657$
$z_n$$9077$$10946$$14701$$28657$$33461$$37666$$43261$$51641$$62210$$75025$
$n$$31$$32$$33$$34$$35$$36$$37$$38$$39$$40$
$x_n$$5$$34$$2$$1$$13$$233$$169$$1$$5$$34$
$y_n$$6466$$1325$$33461$$75025$$7561$$610$$985$$196418$$43261$$9077$
$z_n$$96557$$135137$$195025$$196418$$294685$$426389$$499393$$514229$$646018$$925765$

定数

 正則連分数 $a_0+\dfrac{1}{a_1+\dfrac{1}{\ddots +a_n+\dfrac{1}{\ddots}}}$ を $[a_0;a_1,\cdots,a_n,\cdots ]$ で表す. $\{ a_n\}$ において第 $m+1$ 項以降 $a_{m+1},$ $\cdots,$ $a_{m+l}$ が繰り返されるとき, これを $[a_0;a_1,\cdots,a_m,\dot{a_{m+1}},\cdots,\dot{a_{m+l}}]$ で表す.

累乗根 (正の数)

$2$ の平方根
$\begin{aligned} \sqrt 2 &= [1;\dot 2] \\ &= 1.41421\ 35623\ 73095\ 04880\ 16887\ 24209\ 69807\ 85696\ 71875\ 37694 \\ &\quad\ \ \;\,\,80731\ 76679\ 73799\ 07324\ 78462\ 10703\ 88503\ 87534\ 32764\ 15727\ \cdots \end{aligned}$
$3$ の平方根
$\begin{aligned} \sqrt 3 &= [1;\dot 1,\dot 2] \\ &= 1.73205\ 08075\ 68877\ 29352\ 74463\ 41505\ 87236\ 69428\ 05253\ 81038 \\ &\quad\ \ \;\,\,06280\ 55806\ 97945\ 19330\ 16908\ 80003\ 70811\ 46186\ 75724\ 85756\ \cdots \end{aligned}$
$5$ の平方根
$\begin{aligned} \sqrt 5 &= [2;\dot 4] \\ &= 2.23606\ 79774\ 99789\ 69640\ 91736\ 68731\ 27623\ 54406\ 18359\ 61152 \\ &\quad\ \ \;\,\,57242\ 70897\ 24541\ 05209\ 25637\ 80489\ 94144\ 14408\ 37878\ 22749\ \cdots \end{aligned}$
$2$ の立方根
$\begin{aligned} \sqrt[3]{2} &= [1;3,1,5,1,1,4,1,1,8,1,14,1,10,2,1,4,12,2,3,2,\cdots ] \\ &= 1.25992\ 10498\ 94873\ 16476\ 72106\ 07278\ 22835\ 05702\ 51464\ 70150 \\ &\quad\ \ \;\,\,79800\ 81975\ 11215\ 52996\ 76513\ 95948\ 37293\ 96562\ 43625\ 50941\ \cdots \end{aligned}$
$3$ の立方根
$\begin{aligned} \sqrt[3]{3} &= [1;2,3,1,4,1,5,1,1,6,2,5,8,3,3,4,2,6,4,4,1,\cdots ] \\ &= 1.44224\ 95703\ 07408\ 38232\ 16383\ 10780\ 10958\ 83918\ 69253\ 49935 \\ &\quad\ \ \;\,\,05775\ 46416\ 19454\ 16875\ 96829\ 99733\ 98547\ 55479\ 70564\ 52566\ \cdots \end{aligned}$
$5$ の立方根
$\begin{aligned} \sqrt[3]{5} &= [1;1,2,2,4,3,3,1,5,1,1,4,10,17,1,14,1,1,3052,1,1,\cdots ] \\ &= 1.70997\ 59466\ 76696\ 98935\ 31088\ 72543\ 86010\ 98680\ 55110\ 54305 \\ &\quad\ \ \;\,\,49243\ 82861\ 70744\ 42959\ 20504\ 17321\ 62571\ 87010\ 02018\ 90022\ \cdots \end{aligned}$

重要定数

円周率 $\pi$
$\begin{aligned} \pi &= [3;7,15,1,292,1,1,1,2,1,3,1,14,2,1,1,2,2,2,2,1,\cdots ] \\ &= 3.14159\ 26535\ 89793\ 23846\ 26433\ 83279\ 50288\ 41971\ 69399\ 37510 \\ &\quad\ \ \;\,\,58209\ 74944\ 59230\ 78164\ 06286\ 20899\ 86280\ 34825\ 34211\ 70679\ \cdots \end{aligned}$
レムニスケート周率 $\varpi$
$\begin{aligned} \varpi &= [2;1,1,1,1,1,4,1,2,5,1,1,1,14,9,2,6,2,9,4,1,\cdots ] \\ &= 2.62205\ 75542\ 92119\ 81046\ 48395\ 89891\ 11941\ 36827\ 54951\ 43162 \\ &\quad\ \ \;\,\,31628\ 16821\ 70380\ 07905\ 87070\ 41425\ 02302\ 95532\ 96142\ 90934\ \cdots \end{aligned}$
ネイピア数 (自然対数の底) $e$
$\begin{aligned} e &= [2;1,2,1,1,4,1,1,6,1,1,8,1,1,10,1,1,12,1,1,14,\cdots ] \\ &= 2.71828\ 18284\ 59045\ 23536\ 02874\ 71352\ 66249\ 77572\ 47093\ 69995 \\ &\quad\ \ \;\,\,95749\ 66967\ 62772\ 40766\ 30353\ 54759\ 45713\ 82178\ 52516\ 64274\ \cdots \end{aligned}$
オイラーの定数 $\gamma$
$\begin{aligned} \gamma &= [0;1,1,2,1,2,1,4,3,13,5,1,1,8,1,2,4,1,1,40,1,\cdots ] \\ &= 0.57721\ 56649\ 01532\ 86060\ 65120\ 90082\ 40243\ 10421\ 59335\ 93992 \\ &\quad\ \ \;\,\,35988\ 05767\ 23488\ 48677\ 26777\ 66467\ 09369\ 47063\ 29174\ 67495\ \cdots \end{aligned}$
黄金数 $\phi = \dfrac{1+\sqrt 5}{2}$
$\begin{aligned} \phi &= [1;\dot 1] \\ &= 1.61803\ 39887\ 49894\ 84820\ 45868\ 34365\ 63811\ 77203\ 09179\ 80576 \\ &\quad\ \ \;\,\,28621\ 35448\ 62270\ 52604\ 62818\ 90244\ 97072\ 07204\ 18939\ 11374\ \cdots \end{aligned}$
白銀数 $\tau = 1+\sqrt 2$
$\begin{aligned} \tau &= [2;\dot 2] \\ &= 2.41421\ 35623\ 73095\ 04880\ 16887\ 24209\ 69807\ 85696\ 71875\ 37694 \\ &\quad\ \ \;\,\,80731\ 76679\ 73799\ 07324\ 78462\ 10703\ 88503\ 87534\ 32764\ 15727\ \cdots \end{aligned}$
超黄金数 $\psi = \dfrac{1}{\sqrt[3]{\dfrac{1}{2}+\dfrac{1}{6}\sqrt{\dfrac{31}{3}}}+\sqrt[3]{\dfrac{1}{2}-\dfrac{1}{6}\sqrt{\dfrac{31}{3}}}}$
$\begin{aligned} \psi &= [1;2,6,1,3,5,4,22,1,1,4,1,2,84,1,3,1,6,1,3,1,\cdots ] \\ &= 1.46557\ 12318\ 76768\ 02665\ 67312\ 25219\ 93910\ 80255\ 77568\ 47228 \\ &\quad\ \ \;\,\,57016\ 43183\ 11124\ 92629\ 96685\ 01784\ 04781\ 25801\ 19490\ 92700\ \cdots \end{aligned}$
超白銀数 $\varsigma = \dfrac{1}{\sqrt[3]{\dfrac{1}{2}+\dfrac{1}{6}\sqrt{\dfrac{59}{3}}}+\sqrt[3]{\dfrac{1}{2}-\dfrac{1}{6}\sqrt{\dfrac{59}{3}}}}$
$\begin{aligned} \varsigma &= [2;4,1,6,2,1,1,1,1,1,1,2,2,1,2,1,2,1,27,1654,1,\cdots ] \\ &= 2.20556\ 94304\ 00590\ 31170\ 20286\ 17783\ 82342\ 63771\ 08919\ 59769 \\ &\quad\ \ \;\,\,94404\ 70552\ 20355\ 18347\ 90359\ 16746\ 91764\ 18269\ 57805\ 25078\ \cdots \end{aligned}$
トリボナッチ定数 $\alpha = \dfrac{1}{3}(1+\sqrt[3]{19+3\sqrt{33}}+\sqrt[3]{19-3\sqrt{33}})$
$\begin{aligned} \alpha &= [1;1,5,4,2,305,1,8,2,1,4,6,14,3,1,13,5,1,7,23,1,\cdots ] \\ &= 1.83928\ 67552\ 14161\ 13255\ 18525\ 64653\ 28660\ 04241\ 78746\ 09759 \\ &\quad\ \ \;\,\,22467\ 78758\ 63940\ 42032\ 22081\ 96642\ 57384\ 35419\ 42830\ 70141\ \cdots \end{aligned}$
プラスチック数 $\rho = \sqrt[3]{\dfrac{1}{2}+\dfrac{1}{6}\sqrt{\dfrac{23}{3}}}+\sqrt[3]{\dfrac{1}{2}-\dfrac{1}{6}\sqrt{\dfrac{23}{3}}}$
$\begin{aligned} \rho &= [1;3,12,1,1,3,2,3,2,4,2,141,80,2,5,1,2,8,2,1,1,\cdots ] \\ &= 1.32471\ 79572\ 44746\ 02596\ 09088\ 54478\ 09734\ 07344\ 04056\ 90173 \\ &\quad\ \ \;\,\,33645\ 34015\ 05030\ 28278\ 51245\ 54759\ 40546\ 99347\ 98178\ 72803\ \cdots \end{aligned}$
カラビの三角形定数 $\delta = \dfrac{1}{3}\left( 1+\sqrt[3]{\dfrac{-23+3\sqrt{-237}}{4}}+\sqrt[3]{\dfrac{-23-3\sqrt{-237}}{4}}\right)$
$\begin{aligned} \delta &= [1;1,1,4,2,1,2,1,5,2,1,3,1,1,390,1,1,2,11,6,2,\cdots ] \\ &= 1.55138\ 75245\ 48320\ 39226\ 19525\ 10264\ 62381\ 51635\ 91703\ 80388 \\ &\quad\ \ \;\,\,71995\ 28007\ 12011\ 79267\ 42554\ 25695\ 72957\ 60453\ 61202\ 54362\ \cdots \end{aligned}$
逆フィボナッチ定数 $\psi = \displaystyle\sum_{n = 1}^\infty\dfrac{1}{F_n}$ ($\{ F_n\}$: フィボナッチ数列)
$\begin{aligned} \psi &= [3;2,1,3,1,1,13,2,3,3,2,1,1,6,3,2,4,362,2,4,8,\cdots ] \\ &= 3.35988\ 56662\ 43177\ 55317\ 20113\ 02918\ 92717\ 96889\ 05133\ 73196 \\ &\quad\ \ \;\,\,84864\ 95553\ 81532\ 51303\ 18996\ 68338\ 36154\ 16216\ 45679\ 00872\ \cdots \end{aligned}$
$2$ 個の整数が互いに素である確率 $\dfrac{1}{\zeta (2)} = \dfrac{6}{\pi ^2}$
$\begin{aligned} \frac{1}{\zeta (2)} &= 0.60792\ 71018\ 54026\ 62866\ 32767\ 79258\ 36583\ 34261\ 52648\ 03347 \\ &\quad\ \ \;\,\,92930\ 73654\ 19136\ 50387\ 25773\ 41264\ 71472\ 55643\ 55373\ 10256\ \cdots \end{aligned}$
ヴァルディの定数 $E$ ($\lfloor E^{2^{n+1}}+\dfrac{1}{2}\rfloor$ はシルヴェスター数列の第 $n$ 項)
$\begin{aligned} E &= 1.26408\ 47353\ 05301\ 11307\ 95995\ 84164\ 66949\ 11145\ 60179\ 20906 \\ &\quad\ \ \;\,\,55331\ 53456\ 41990\ 77590\ 16362\ 95160\ 14226\ 39092\ 68398\ 51504\ \cdots \end{aligned}$
ミルズの定数 $A$ ($\lfloor A^{3^n}\rfloor$ はすべて素数, リーマン予想が真であると仮定した場合の値)
$\begin{aligned} A &= 1.30637\ 78838\ 63080\ 69046\ 86144\ 92602\ 60571\ 29167\ 84585\ 15671 \\ &\quad\ \ \;\,\,36443\ 68053\ 75996\ 64340\ 53766\ 82659\ 88215\ 01403\ 70119\ 73957\ \cdots \end{aligned}$
平面の円による最密充填密度 $\dfrac{\pi}{2\sqrt 3}$
$\begin{aligned} \dfrac{\pi}{2\sqrt 3} &= 0.90689\ 96821\ 17108\ 92529\ 70391\ 28821\ 07786\ 61420\ 33124\ 04637 \\ &\quad\ \ \;\,\,02877\ 84942\ 46769\ 40615\ 90563\ 17694\ 18420\ 62494\ 10603\ 00844\ \cdots \end{aligned}$
空間の球による最密充填密度 $\dfrac{\pi}{3\sqrt 2}$
$\begin{aligned} \dfrac{\pi}{3\sqrt 2} &= 0.74048\ 04896\ 93061\ 04116\ 93134\ 98343\ 44894\ 97691\ 03614\ 89594 \\ &\quad\ \ \;\,\,83705\ 14232\ 60115\ 94057\ 98849\ 91231\ 84292\ 21155\ 79412\ 75395\ \cdots \end{aligned}$
単位線分上の線分の長さの平均値 $R_1 = \dfrac{1}{3}$
$R_1 = 0.\dot{3}$
単位正方形上の線分の長さの平均値 $R_2 = \dfrac{2+\sqrt 2+5\log (1+\sqrt 2)}{15}$
$\begin{aligned} R_2 &= 0.52140\ 54331\ 64720\ 67833\ 09823\ 56607\ 24397\ 49140\ 31567\ 77900 \\ &\quad\ \ \;\,\,83417\ 96210\ 51875\ 05078\ 93304\ 81583\ 18679\ 28132\ 92526\ 14524\ \cdots \end{aligned}$
単位立方体内の線分の長さの平均値 (ロビンズの定数) $R_3 = \dfrac{4+17\sqrt 2-6\sqrt 3+21\log (1+\sqrt 2)+42\log (2+\sqrt 3)-7\pi}{105}$
$\begin{aligned} R_3 &= 0.66170\ 71822\ 67176\ 23515\ 58311\ 33248\ 41358\ 17464\ 00135\ 79095 \\ &\quad\ \ \;\,\,36048\ 08944\ 22947\ 95846\ 46138\ 59763\ 13066\ 52480\ 76810\ 71201\ \cdots \end{aligned}$
単位円上の線分の長さの平均値 $\dfrac{128}{45\pi}$
$\begin{aligned} \frac{128}{45\pi} &= 0.90541\ 47873\ 67226\ 79904\ 07609\ 64963\ 63725\ 95738\ 14873\ 54570 \\ &\quad\ \ \;\,\,77973\ 20063\ 11286\ 83906\ 70985\ 82206\ 62904\ 25189\ 07023\ 97778\ \cdots \end{aligned}$
単位球内の線分の長さの平均値 $\dfrac{36}{35}$
$\dfrac{36}{35} = 1.0\dot{2}8571\dot{4}$

多項式

直交多項式

第 $1$ 種チェビシェフ多項式 $T_n(x)$
[初期値, 漸化式]
$T_0(x) = 1,$ $T_1(x) = x,$ $T_{n+2}(x) = 2xT_{n+1}(x)-T_n(x).$ 
[性質]
$\cos n\theta = T_n(\cos\theta ).$ 
  • $T_0(x) = 1$
  • $T_1(x) = x$
  • $T_2(x) = 2x^2-1$
  • $T_3(x) = 4x^3-3x$
  • $T_4(x) = 8x^4-8x^2+1$
  • $T_5(x) = 16x^5-20x^3+5x$
  • $T_6(x) = 32x^6-48x^4+18x^2-1$
  • $T_7(x) = 64x^7-112x^5+56x^3-7x$
  • $T_8(x) = 128x^8-256x^6+160x^4-32x^2+1$
  • $T_9(x) = 256x^9-576x^7+432x^5-120x^3+9x$
  • $T_{10}(x) = 512x^{10}-1280x^8+1120x^6-400x^4+50x^2-1$
第 $2$ 種チェビシェフ多項式 $U_n(x)$
[初期値, 漸化式]
$U_0(x) = 1,$ $U_1(x) = 2x,$ $U_{n+2}(x) = 2xU_{n+1}(x)-U_n(x).$ 
[性質]
$\sin (n+1)\theta = \sin\theta\cdot U_n(\cos\theta ).$ 
  • $U_0(x) = 1$
  • $U_1(x) = 2x$
  • $U_2(x) = 4x^2-1$
  • $U_3(x) = 8x^3-4x$
  • $U_4(x) = 16x^4-12x^2+1$
  • $U_5(x) = 32x^5-32x^3+6x$
  • $U_6(x) = 64x^6-80x^4+24x^2-1$
  • $U_7(x) = 128x^7-192x^5+80x^3-8x$
  • $U_8(x) = 256x^8-448x^6+240x^4-40x^2+1$
  • $U_9(x) = 512x^9-1024x^7+672x^5-160x^3+10x$
  • $U_{10}(x) = 1024x^{10}-2304x^8+1792x^6-560x^4+60x^2-1$
ルジャンドル多項式 $P_n(x)$
[初期値, 漸化式]
$P_0(x) = 1,$ $P_1(x) = x,$ 
$(n+2)P_{n+2}(x) = (2n+3)xP_{n+1}(x)-(n+1)P_n(x).$ 
[性質]
ルジャンドルの微分方程式を満たす.
  • $P_0(x) = 1$
  • $P_1(x) = x$
  • $2P_2(x) = 3x^2-1$
  • $2P_3(x) = 5x^3-3x$
  • $8P_4(x) = 35x^4-30x^2+3$
  • $8P_5(x) = 63x^5-70x^3+15x$
  • $16P_6(x) = 231x^6-315x^4+105x^2-5$
  • $16P_7(x) = 429x^7-693x^5+315x^3-35x$
  • $128P_8(x) = 6435x^8-12012x^6+6930x^4-1260x^2+35$
  • $128P_9(x) = 12155x^9-25740x^7+18018x^5-4620x^3+315x$
  • $256P_{10}(x) = 46189x^{10}-109395x^8+90090x^6-30030x^4+3465x^2-63$

整数論

ベルヌーイ多項式 $B_n(x)$
[性質]
$\displaystyle\int_x^{x+1}B_n(t)dt = x^n.$ 
  • $B_0(x) = 1$
  • $B_1(x) = x-\dfrac{1}{2}$
  • $B_2(x) = x^2-x+\dfrac{1}{6}$
  • $B_3(x) = x^3-\dfrac{3}{2}x^2+\dfrac{1}{2}x$
  • $B_4(x) = x^4-2x^3+x^2-\dfrac{1}{30}$
  • $B_5(x) = x^5-\dfrac{5}{2}x^4+\dfrac{5}{3}x^3-\dfrac{1}{6}x$
  • $B_6(x) = x^6-3x^5+\dfrac{5}{2}x^4-\dfrac{1}{2}x^2+\dfrac{1}{42}$
  • $B_7(x) = x^7-\dfrac{7}{2}x^6+\dfrac{7}{2}x^5-\dfrac{7}{6}x^3+\dfrac{1}{6}x$
  • $B_8(x) = x^8-4x^7+\dfrac{14}{3}x^6-\dfrac{7}{3}x^4+\dfrac{2}{3}x^2-\dfrac{1}{30}$
  • $B_9(x) = x^9-\dfrac{9}{2}x^8+6x^7-\dfrac{21}{5}x^5+2x^3-\dfrac{3}{10}x$
  • $B_{10}(x) = x^{10}-5x^9+\dfrac{15}{2}x^8-7x^6+5x^4-\dfrac{3}{2}x^2+\dfrac{5}{66}$
$n$ 番目までの $m$ 乗数の和を表す多項式 $S_m(n)$
  • $S_0(n) = n$
  • $S_1(n) = \dfrac{1}{2}n(n+1)$
  • $S_2(n) = \dfrac{1}{6}n(n+1)(2n+1)$
  • $S_3(n) = \dfrac{1}{4}n^2(n+1)^2$
  • $S_4(n) = \dfrac{1}{30}n(n+1)(2n+1)(3n^2+3n-1)$
  • $S_5(n) = \dfrac{1}{12}n^2(n+1)^2(2n^2+2n-1)$
  • $S_6(n) = \dfrac{1}{42}n(n+1)(2n+1)(3n^4+6n^3-3n+1)$
  • $S_7(n) = \dfrac{1}{24}n^2(n+1)^2(3n^4+6n^3-n^2-4n+2)$
  • $S_8(n) = \dfrac{1}{90}n(10n^8+45n^7+60n^6-42n^4+20n^2-3)$
  • $S_9(n) = \dfrac{1}{20}n^2(n+1)^2(n^2+n-1)(2n^4+4n^3-n^2-3n+3)$
  • $S_{10}(n) = \dfrac{1}{66}n(6n^{10}+33n^9+55n^8-66n^4-33n^2+5)$