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.

A355463 Expansion of Sum_{k>=0} (x/(1 - k^k * x))^k.

Original entry on oeis.org

1, 1, 2, 10, 131, 5656, 869097, 490286392, 1264458639313, 12443651667592768, 681538604797281047489, 153070077563816488157872384, 205935348854901274982393017521537, 1352544986573612111579941739713633174912
Offset: 0

Views

Author

Seiichi Manyama, Jul 03 2022

Keywords

Crossrefs

Programs

  • Mathematica
    Flatten[{1, Table[Sum[Binomial[n-1,k-1] * k^(k*(n-k)), {k,1,n}], {n,1,20}]}] (* Vaclav Kotesovec, Feb 16 2023 *)
  • PARI
    my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (x/(1-k^k*x))^k))
    
  • PARI
    a(n) = if(n==0, 1, sum(k=1, n, k^(k*(n-k))*binomial(n-1, k-1)));

Formula

a(n) = Sum_{k=1..n} k^(k*(n-k)) * binomial(n-1,k-1) for n > 0.

A355473 Expansion of Sum_{k>=0} x^k/(1 - k^3 * x)^(k+1).

Original entry on oeis.org

1, 1, 3, 28, 497, 12736, 517297, 28793248, 2095968065, 199522773568, 23839495688321, 3482169003693304, 616298415199306369, 130134007837039167040, 32272959284595295173377, 9313050358489324003967176, 3101245112865402456422252033
Offset: 0

Views

Author

Seiichi Manyama, Jul 03 2022

Keywords

Crossrefs

Programs

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

Formula

E.g.f.: Sum_{k>=0} exp(k^3 * x) * x^k/k!.
a(n) = Sum_{k=0..n} k^(3*(n-k)) * binomial(n,k).

A360935 Expansion of e.g.f. Sum_{k>=0} exp((k^k - 1)*x) * x^k/k!.

Original entry on oeis.org

1, 1, 1, 10, 159, 8306, 1346855, 801620870, 2064941077199, 20691706495244482, 1137052204448926181679, 255128692791512749880418782, 348784909594653094321340422905383, 2262992285674206001784964011734257207938
Offset: 0

Views

Author

Seiichi Manyama, Feb 26 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(1+x+sum(k=2, N, exp((k^k-1)*x)*x^k/k!)))
    
  • PARI
    my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, x^k/(1-(k^k-1)*x)^(k+1)))
    
  • PARI
    a(n) = sum(k=0, n, (k^k-1)^(n-k)*binomial(n, k));

Formula

G.f.: Sum_{k>=0} x^k/(1 - (k^k - 1)*x)^(k+1).
a(n) = Sum_{k=0..n} (k^k - 1)^(n-k) * binomial(n,k).
Showing 1-3 of 3 results.