A378378 a(n) = Sum_{k=0..n} binomial(n,k) * binomial(n+3*k-1,3*k).

1, 2, 16, 170, 1920, 22402, 266800, 3222634, 39328768, 483752258, 5987236816, 74474238698, 930212870784, 11659157743170, 146567181170160, 1847198697449770, 23332153206562816, 295286370825453442, 3743540075432798608, 47532529217041519658, 604366048841146280320

Offset

0,2

Links

Table of n, a(n) for n=0..20.

Formula

a(n) = hypergeom([(1+n)/3, (2+n)/3, -n, n/3], [1/3, 2/3, 1], -1). - Stefano Spezia, Nov 24 2024

Mathematica

a[n_]:=HypergeometricPFQ[{(1+n)/3, (2+n)/3, -n, n/3}, {1/3, 2/3, 1}, -1]; Array[a, 21, 0] (* Stefano Spezia, Nov 24 2024 *)

Prog

(PARI) a(n) = sum(k=0, n, binomial(n, k)*binomial(n+3*k-1, 3*k));

Crossrefs

Main diagonal of A378318.

Cf. A123164, A333473.

Sequence in context: A215702 A155659 A108999 * A355408 A367384 A138014

Adjacent sequences: A378375 A378376 A378377 * A378379 A378380 A378381

Keyword

nonn

Author

Seiichi Manyama, Nov 24 2024

Status

approved