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.

Showing 1-2 of 2 results.

A305275 Coefficients in asymptotic expansion of sequence A302557.

Original entry on oeis.org

1, 0, 2, 6, 35, 256, 2187, 21620, 243947, 3098528, 43799819, 682540780, 11630529643, 215190967544, 4296657514283, 92083313483300, 2108244638675035, 51350077108834832, 1325682930813985547, 36157047428501464220, 1038793351537388253211, 31354977545074731373512
Offset: 0

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Author

Vaclav Kotesovec, Aug 18 2018

Keywords

Examples

			A302557(n) / (exp(-1) * n!) ~ 1 + 2/n^2 + 6/n^3 + 35/n^4 + 256/n^5 + 2187/n^6 + ...
		

Crossrefs

Formula

a(k) ~ k! / (2 * exp(1) * (log(2))^(k+1)).

A328007 Expansion of e.g.f. 1 / (2 - exp(-x) / (1 - x)).

Original entry on oeis.org

1, 0, 1, 2, 15, 84, 705, 6222, 65779, 765608, 9999333, 143009250, 2235857943, 37833382716, 689729792713, 13469761663862, 280613761282875, 6211105772020560, 145566258957724845, 3601055676894146442, 93772841089130278495, 2563969299245947753700, 73443322391840827563921
Offset: 0

Views

Author

Ilya Gutkovskiy, Oct 01 2019

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 22; CoefficientList[Series[1/(2 - Exp[-x]/(1 - x)), {x, 0, nmax}], x] Range[0, nmax]!
    a[0] = 1; a[n_] := a[n] = Sum[Binomial[n, k] Subfactorial[k] a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 22}]
  • PARI
    my(x='x+O('x^25)); Vec(serlaplace(1 / (2 - exp(-x) / (1 - x)))) \\ Michel Marcus, Oct 02 2019

Formula

a(0) = 1; a(n) = Sum_{k=1..n} binomial(n,k) * A000166(k) * a(n-k).
a(n) ~ n! * (-LambertW(-exp(-1)/2) / (2*(1 + LambertW(-exp(-1)/2))^(n+2))). - Vaclav Kotesovec, Oct 02 2019
Showing 1-2 of 2 results.