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.

A355494 Expansion of Sum_{k>=0} (k * x/(1 - x))^k.

Original entry on oeis.org

1, 1, 5, 36, 350, 4328, 65132, 1155904, 23640724, 547544032, 14166236708, 404944248104, 12674392793900, 431104742439088, 15834117059443828, 624575921756875960, 26332801242942780668, 1181750740315156943936, 56244454481507648435012
Offset: 0

Views

Author

Seiichi Manyama, Jul 04 2022

Keywords

Crossrefs

Programs

  • Mathematica
    Join[{1}, Table[Sum[k^k * Binomial[n-1,k-1], {k,1,n}], {n, 1, 20}]] (* Vaclav Kotesovec, Jul 05 2022 *)
  • PARI
    my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k*x/(1-x))^k))
    
  • PARI
    a(n) = if(n==0, 1, sum(k=1, n, k^k*binomial(n-1, k-1)));

Formula

a(n) = Sum_{k=1..n} k^k * binomial(n-1,k-1) for n > 0.
a(n) ~ exp(exp(-1)) * n^n. - Vaclav Kotesovec, Jul 05 2022

A355496 Expansion of Sum_{k>=0} (k^3 * x/(1 - x))^k.

Original entry on oeis.org

1, 1, 65, 19812, 16836458, 30584805344, 101712712528352, 559155681922806328, 4726278437746021089208, 58187531579876705928027712, 1000523517685151396828602120640, 23235157037192774575979788565151104, 709057406693306876515431403267191583808
Offset: 0

Views

Author

Seiichi Manyama, Jul 04 2022

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k^3*x/(1-x))^k))
    
  • PARI
    a(n) = if(n==0, 1, sum(k=1, n, k^(3*k)*binomial(n-1, k-1)));

Formula

a(n) = Sum_{k=1..n} k^(3*k) * binomial(n-1,k-1) for n > 0.
Showing 1-2 of 2 results.