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.

A266497 Binomial transform of A015128.

Original entry on oeis.org

1, 3, 9, 27, 79, 225, 627, 1717, 4633, 12341, 32501, 84737, 218959, 561263, 1428287, 3610671, 9072367, 22668285, 56345835, 139382713, 343242533, 841713531, 2055944117, 5003148987, 12132552115, 29323810757, 70651867863, 169719163521, 406541986857, 971192810019
Offset: 0

Views

Author

Vaclav Kotesovec, Dec 30 2015

Keywords

Crossrefs

Programs

  • Mathematica
    A015128[n_]:=Sum[PartitionsP[n-k]*PartitionsQ[k], {k, 0, n}];
    Table[Sum[Binomial[n, k]*A015128[k], {k, 0, n}], {n, 0, 30}]

Formula

a(n) ~ 2^(n-2) * exp(Pi*sqrt(n/2) + Pi^2/16) / n.
a(n) = [x^n] (1 + x)^n/theta_4(x), where theta_4() is the Jacobi theta function. - Ilya Gutkovskiy, Apr 20 2018

A307945 Exponential convolution of A015128 with themselves.

Original entry on oeis.org

1, 4, 16, 64, 252, 968, 3616, 13120, 46432, 160772, 545856, 1821056, 5979520, 19350552, 61795968, 194964672, 608261628, 1878140024, 5743681784, 17408223328, 52320105080, 156011658272, 461763417056, 1357182242560, 3962591708576, 11497241014652
Offset: 0

Views

Author

Vaclav Kotesovec, May 07 2019

Keywords

Crossrefs

Programs

  • Maple
    S:= series(1/JacobiTheta4(0,q),q,101):
    f:= n -> add(binomial(n,k)*coeff(S,q,k)*coeff(S,q,n-k),k=0..n):
    map(f, [$0..100]); # Robert Israel, May 08 2019
  • Mathematica
    A015128[n_]:=Sum[PartitionsP[n-k]*PartitionsQ[k], {k, 0, n}]; Table[Sum[Binomial[n, k]*A015128[k]*A015128[n-k], {k, 0, n}], {n, 0, 25}]

Formula

a(n) = Sum_{k=0..n} binomial(n,k) * A015128(k) * A015128(n-k).
a(n) ~ 2^(n-4) * exp(Pi*sqrt(2*n)) / n^2.
Showing 1-2 of 2 results.