A367049 G.f. satisfies A(x) = 1 + x*A(x)^4 + x^2*A(x)^2.

1, 1, 5, 28, 187, 1361, 10479, 83914, 691738, 5830903, 50028259, 435454040, 3835732631, 34128555184, 306276957665, 2769050552948, 25197515469820, 230599623819217, 2121066298440282, 19597929365099640, 181814132152022195, 1692920612932871541

Offset: 0

Author

Seiichi Manyama, Nov 03 2023

Keywords

• nonn

Crossrefs

Cf. A365178, A365180, A365181, A365182, A365183, A367041, A367048, A367050.

Programs

PARI

a(n) = sum(k=0, n\2, binomial(3*n-4*k+1, k)*binomial(4*n-6*k, n-2*k)/(3*n-4*k+1));

Formula

a(n) = Sum_{k=0..floor(n/2)} binomial(3*n-4*k+1,k) * binomial(4*n-6*k,n-2*k)/(3*n-4*k+1).