A367061 G.f. satisfies A(x) = 1 + x*A(x)^3 + x^3*A(x)^5.

1, 1, 3, 13, 63, 328, 1797, 10210, 59607, 355409, 2155166, 13250055, 82402013, 517453773, 3276534510, 20897024350, 134118458191, 865574280977, 5613879001983, 36571135386965, 239187418784442, 1569994174618799, 10338925554033967, 68288387553861826

Offset: 0

Author

Seiichi Manyama, Nov 04 2023

Keywords

• nonn

Crossrefs

Cf. A366676, A367057, A367058, A367059, A367060, A367062.

Programs

PARI

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

Formula

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