A356342 a(n) = Sum_{k=1..n} binomial(2*n, k) * sigma_2(k).

2, 34, 281, 2178, 12397, 79729, 398932, 2224354, 10959221, 56341309, 255685080, 1334248401, 5892916876, 28082515768, 127714609741, 604178948098, 2590365128017, 12284868071365, 52160408294826, 241445420212893, 1049251819301974, 4674022621994716, 19563451165603647

Offset

1,1

Links

Table of n, a(n) for n=1..23.

Formula

a(n) ~ zeta(3) * n^2 * 2^(2*n-1).

Mathematica

Table[Sum[Binomial[2*n, k]*DivisorSigma[2, k], {k, 1, n}], {n, 1, 30}]

Prog

(PARI) a(n) = sum(k=1, n, binomial(2*n, k) * sigma(k, 2)); \\ Michel Marcus, Aug 05 2022

Crossrefs

Cf. A001157, A064602, A351146, A356038.

Sequence in context: A220507 A263689 A098531 * A296995 A301611 A224294

Adjacent sequences: A356339 A356340 A356341 * A356343 A356344 A356345

Keyword

nonn

Author

Vaclav Kotesovec, Aug 04 2022

Status

approved