cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A332408 a(n) = Sum_{k=0..n} binomial(n,k) * k! * k^n.

Original entry on oeis.org

1, 1, 10, 213, 8284, 513105, 46406286, 5772636373, 945492503320, 197253667623681, 51069324556151290, 16067283861476491941, 6037615013420387657844, 2670812587802323522405393, 1373842484756310928089102022, 813119045938378747809030359445
Offset: 0

Views

Author

Ilya Gutkovskiy, Apr 23 2020

Keywords

Crossrefs

Programs

  • Mathematica
    Join[{1}, Table[Sum[Binomial[n, k] k! k^n, {k, 0, n}], {n, 1, 15}]]
  • PARI
    a(n) = sum(k=0, n, binomial(n,k) * k! * k^n); \\ Michel Marcus, Apr 24 2020
    
  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(sum(k=0, N, (k*x*exp(x))^k))) \\ Seiichi Manyama, Feb 19 2022

Formula

G.f.: Sum_{k>=0} k! * k^k * x^k / (1 - k*x)^(k+1).
a(n) = n! * Sum_{k=0..n} k^n / (n-k)!.
a(n) ~ c * n! * n^n, where c = A073229 = exp(exp(-1)). - Vaclav Kotesovec, Feb 20 2021
E.g.f.: Sum_{k>=0} (k*x*exp(x))^k. - Seiichi Manyama, Feb 19 2022

A277510 E.g.f.: -1/(1-LambertW(-x))^2.

Original entry on oeis.org

-1, 2, -2, 6, 8, 170, 1872, 29246, 519808, 10698642, 248787200, 6458737142, 185138721792, 5808233422394, 197952647108608, 7283047491096750, 287705410381709312, 12145740050403520034, 545696709922799419392, 25998534614835587104742, 1309210567403228200960000
Offset: 0

Views

Author

Vaclav Kotesovec, Oct 18 2016

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[-1/(1-LambertW[-x])^2, {x, 0, 20}], x] * Range[0, 20]!
  • PARI
    x='x+O('x^50); Vec(serlaplace(-1/(1 - lambertw(-x))^2)) \\ G. C. Greubel, Nov 08 2017

Formula

a(n) ~ n^(n-1) / 4.

A277490 E.g.f.: -1/(1+LambertW(-x)^2).

Original entry on oeis.org

-1, 0, 2, 12, 72, 520, 5040, 67284, 1156736, 23655888, 549676800, 14216252380, 405068387328, 12624364306008, 427599019108352, 15646376279614500, 615155126821355520, 25861820048469628576, 1157706908035331457024, 54977324662490442177708, 2760439046217459138560000
Offset: 0

Views

Author

Vaclav Kotesovec, Oct 17 2016

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[-1/(1+LambertW[-x]^2), {x, 0, 20}], x] * Range[0, 20]!
  • PARI
    x='x+O('x^50); Vec(serlaplace(-1/(1 + lambertw(-x)^2))) \\ G. C. Greubel, Nov 08 2017

Formula

a(n) ~ n^(n-1) / 2.

A295098 a(n) = n! * [x^n] exp(n*x)*(1 + exp(x^2/2)*x*(1 + sqrt(Pi/2)*erf(x/sqrt(2)))).

Original entry on oeis.org

1, 2, 10, 75, 760, 9715, 150060, 2719017, 56556480, 1328337117, 34773226340, 1003998156293, 31696623421488, 1086258754644505, 40161805428662876, 1593475984997421525, 67534151717002711296, 3044989873158805787409, 145537456143562934305860, 7350253384336351186239341, 391132792671917087054081200
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 14 2017

Keywords

Comments

The n-th term of the n-th binomial transform of A006882.

Crossrefs

Programs

  • Mathematica
    Table[n! SeriesCoefficient[Exp[n x] (1 + Exp[x^2/2] x (1 + Sqrt[Pi/2] Erf[x/Sqrt[2]])), {x, 0, n}], {n, 0, 20}]

Formula

a(n) ~ c * n^n, where c = 1 + exp(1/2) * (1 + sqrt(Pi/2) * erf(1/sqrt(2))) = 4.0594074053425761445394754992332... - Vaclav Kotesovec, Aug 21 2018

A295099 a(n) = n! * [x^n] exp(n*x)/sqrt(1 - 2*x).

Original entry on oeis.org

1, 2, 11, 96, 1145, 17320, 317547, 6843872, 169603793, 4752704160, 148631984075, 5132717953792, 194022218612169, 7969667589513344, 353510496652374635, 16842274069331520000, 857827370723082312737, 46516913938434654949888, 2675772791433589181094027, 162742831545094476694814720
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 14 2017

Keywords

Comments

The n-th term of the n-th binomial transform of A001147.

Crossrefs

Programs

  • Mathematica
    Table[n! SeriesCoefficient[Exp[n x]/Sqrt[1 - 2 x], {x, 0, n}], {n, 0, 19}]

Formula

a(n) ~ 2^(n+1) * n^n / exp(n/2). - Vaclav Kotesovec, Nov 14 2017

A295100 a(n) = n! * [x^n] exp(n*x)/(1 - 2*x).

Original entry on oeis.org

1, 3, 20, 201, 2688, 44815, 894528, 20792205, 551518208, 16438822587, 543934387200, 19783668211153, 784536321392640, 33689132092480839, 1557397919735103488, 77117362592836807125, 4072280214605427376128, 228441851811771488284915, 13566762607790788699226112, 850372121882700252639269337
Offset: 0

Views

Author

Ilya Gutkovskiy, Nov 14 2017

Keywords

Comments

The n-th term of the n-th binomial transform of A000165.

Crossrefs

Programs

  • Maple
    S:= series(exp(n*x)/(1-2*x),x,51):
    seq(n!*coeff(S,x,n),n=0..50); # Robert Israel, Nov 14 2017
  • Mathematica
    Table[n! SeriesCoefficient[Exp[n x]/(1 - 2 x), {x, 0, n}], {n, 0, 19}]

Formula

a(n) ~ 2^n * exp(n/2) * n!. - Vaclav Kotesovec, Nov 14 2017
a(n) = n! * Sum_{k=0..n} n^k*2^(n-k)/k! = 2^n*Gamma(n+1, n/2)*exp(n/2). - Robert Israel, Nov 14 2017

A331690 a(n) = Sum_{k=0..n} Stirling2(n,k) * k! * n^(n - k).

Original entry on oeis.org

1, 1, 4, 33, 456, 9445, 272448, 10386817, 503758720, 30202999821, 2189000524800, 188349613075393, 18954958449853440, 2203304642871358741, 292675996808408743936, 44022321302156791898625, 7438113993194856900034560, 1401876939543892434209075581
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 24 2020

Keywords

Crossrefs

Programs

  • Mathematica
    Join[{1}, Table[Sum[StirlingS2[n, k] k! n^(n - k), {k, 0, n}], {n, 1, 17}]]
    Table[SeriesCoefficient[Sum[k! x^k/Product[(1 - n j x), {j, 1, k}], {k, 0, n}], {x, 0, n}], {n, 0, 17}]
    Join[{1}, Table[n^(n + 1) PolyLog[-n, 1/(n + 1)]/(n + 1), {n, 1, 17}]]
  • PARI
    a(n) = sum(k=0, n, stirling(n, k, 2)*k!*n^(n-k)); \\ Michel Marcus, Jan 24 2020

Formula

a(n) = [x^n] Sum_{k>=0} k! * x^k / Product_{j=1..k} (1 - n*j*x).
a(n) = n! * [x^n] n / (1 + n - exp(n*x)) for n > 0.
a(n) = n^(n + 1) * Sum_{k>=1} k^n / (n + 1)^(k + 1) for n > 0.
a(n) ~ n! * n^(n+1) / ((n+1) * log(n+1)^(n+1)). - Vaclav Kotesovec, Jun 06 2022

A336949 a(n) = n! * [x^n] 1 / (exp(-n*x) - x).

Original entry on oeis.org

1, 2, 14, 195, 4440, 147745, 6698448, 394852577, 29250137472, 2652483234033, 288363456748800, 36952298766628465, 5504130616452258816, 941845623036360908489, 183298110723156455921664, 40221612394630225987208625, 9876429434585097671993032704
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 08 2020

Keywords

Crossrefs

Programs

  • Mathematica
    Table[n! SeriesCoefficient[1/(Exp[-n x] - x), {x, 0, n}], {n, 0, 16}]
    Join[{1}, Table[n! Sum[(n (n - k + 1))^k/k!, {k, 0, n}], {n, 1, 16}]]
  • PARI
    a(n)={n!*polcoef(1/(exp(-n*x + O(x*x^n)) - x), n)} \\ Andrew Howroyd, Aug 08 2020

Formula

a(n) = n! * Sum_{k=0..n} (n * (n-k+1))^k / k!.

A219546 Schenker primes.

Original entry on oeis.org

5, 13, 23, 31, 37, 41, 43, 47, 53, 59, 61, 71, 79, 101, 103, 107, 109, 127, 137, 149, 157, 163, 173, 179, 181, 191, 197, 199, 211, 223, 229, 241, 251, 257, 263, 271, 277, 283, 293, 311, 317, 337, 349, 353, 359, 367, 383, 397, 401, 409, 419, 421, 431, 439, 461
Offset: 1

Views

Author

Jonathan Sondow, Nov 22 2012

Keywords

Comments

Amdeberhan, Callan, and Moll (2012) call a prime p a Schenker prime if p divides A063170(r) (the r-th Schenker sum with n-th term) for some r < p.
For any non-Schenker prime p, Amdeberhan, Callan, and Moll (2012) give a formula for the p-adic valuation of any Schenker sum with n-th term.

Examples

			5 is a Schenker prime because 2 < 5 and 5 divides A063170(2) = 10.
17 is not a Schenker prime because 17 is not a factor of A063170(1) = 2, or of A063170(2) = 10, . . . , or of A063170(16) = 105224992014096760832.
		

Crossrefs

Cf. A063170.

Programs

  • Mathematica
    pmax = 300; A063170 = Table[n!*Sum[n^k/k!, {k, 0, n}], {n, 1, pmax}]; Rest[Select[Table[If[PrimeQ[j] && SelectFirst[Range[j], Divisible[A063170[[#]], j] &] != j, j, 0], {j, 1, pmax}], # != 0 &]] (* Vaclav Kotesovec, Nov 30 2017 *)

Extensions

More terms from Vaclav Kotesovec, Nov 30 2017

A308330 a(n) = n! * [x^n] exp(exp(n*x)/(1 - x) - 1).

Original entry on oeis.org

1, 2, 19, 346, 10217, 441226, 26023123, 1998840586, 193094418161, 22841006706928, 3239088790361491, 541309430523114804, 105106521730010262745, 23431755937256853296514, 5936989025261397848036755, 1694791457312643753292004446, 540937403928198054978670965089
Offset: 0

Views

Author

Ilya Gutkovskiy, May 20 2019

Keywords

Crossrefs

Programs

  • Mathematica
    Table[n! SeriesCoefficient[Exp[Exp[n x]/(1 - x) - 1], {x, 0, n}], {n, 0, 16}]
Previous Showing 11-20 of 24 results. Next