A391406 Expansion of g^4/(1 + x*g), where g = 1+x*g^3 is the g.f. of A001764.

1, 3, 14, 68, 352, 1895, 10509, 59619, 344380, 2018599, 11976479, 71786394, 434049233, 2644251959, 16214959902, 100008206636, 619980261922, 3861037683008, 24144159455460, 151540706064143, 954348342189353, 6028591984661431, 38189462008586184, 242544213458754883

Offset

0,2

Links

Table of n, a(n) for n=0..23.

Formula

a(n) = Sum_{k=0..n} (-1)^k * (k+4) * binomial(3*n-2*k+4,n-k)/(3*n-2*k+4).

Prog

(PARI) a(n) = sum(k=0, n, (-1)^k*(k+4)*binomial(3*n-2*k+4, n-k)/(3*n-2*k+4));

Crossrefs

Cf. A023053, A391294, A391404.

Cf. A001558, A001764.

Sequence in context: A241478 A113140 A151324 * A121185 A276904 A199314

Adjacent sequences: A391403 A391404 A391405 * A391407 A391408 A391409

Keyword

nonn

Author

Seiichi Manyama, Dec 08 2025

Status

approved