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 1-3 of 3 results.

A367881 Expansion of e.g.f. 1/(1 - 3 * x * (exp(x) - 1)).

Original entry on oeis.org

1, 0, 6, 9, 228, 1095, 23238, 215481, 4657992, 66216555, 1553967210, 29793656013, 777115661292, 18608934688383, 542832959656302, 15470567460571905, 503794462155308688, 16557037363336856019, 598704921471691072242, 22205328374455141122165
Offset: 0

Views

Author

Seiichi Manyama, Dec 03 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n) = n!*sum(k=0, n\2, 3^k*k!*stirling(n-k, k, 2)/(n-k)!);

Formula

a(0) = 1; a(n) = 3 * n * Sum_{k=2..n} binomial(n-1,k-1) * a(n-k).
a(n) = n! * Sum_{k=0..floor(n/2)} 3^k * k! * Stirling2(n-k,k)/(n-k)!.

A375683 Expansion of e.g.f. 1 / (1 + x * (exp(x) - 1)).

Original entry on oeis.org

1, 0, -2, -3, 20, 115, -306, -6307, -6616, 462663, 2956130, -38945951, -656504388, 2325876683, 145820995670, 562691968005, -33452317341616, -449954883966065, 7055017491780810, 233802046526955497, -571834988279277340, -112474674691684827501
Offset: 0

Views

Author

Seiichi Manyama, Aug 24 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(1+x*(exp(x)-1))))
    
  • PARI
    a(n) = n!*sum(k=0, n\2, (-1)^k*k!*stirling(n-k, k, 2)/(n-k)!);

Formula

a(0) = 1; a(n) = -n * Sum_{k=2..n} binomial(n-1,k-1) * a(n-k).
a(n) = n! * Sum_{k=0..floor(n/2)} (-1)^k * k! * Stirling2(n-k,k)/(n-k)!.

A375695 Expansion of e.g.f. 1 / sqrt(1 - 2 * x * (exp(x) - 1)).

Original entry on oeis.org

1, 0, 2, 3, 40, 185, 2436, 20797, 307616, 3869217, 66259900, 1091351261, 21671302368, 437191547377, 9981020325836, 236821065758565, 6144729994822336, 167019469703969345, 4868403452056231164, 148845363155530699789, 4822574537456548631360
Offset: 0

Views

Author

Seiichi Manyama, Aug 24 2024

Keywords

Crossrefs

Programs

  • Mathematica
    With[{nn=20},CoefficientList[Series[1/Sqrt[1-2x (Exp[x]-1)],{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Feb 06 2025 *)
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(1/sqrt(1-2*x*(exp(x)-1))))
    
  • PARI
    a001147(n) = prod(k=0, n-1, 2*k+1);
    a(n) = n!*sum(k=0, n, a001147(k)*stirling(n-k, k, 2)/(n-k)!);

Formula

a(n) = n! * Sum_{k=0..floor(n/2)} A001147(k) * Stirling2(n-k,k)/(n-k)!.
Showing 1-3 of 3 results.