A367041 G.f. satisfies A(x) = 1 + x^2 + x*A(x)^4.

1, 1, 5, 26, 168, 1195, 8988, 70318, 566388, 4665221, 39113732, 332691758, 2863778072, 24900264326, 218372530380, 1929363592870, 17157018725000, 153442147343648, 1379250344938676, 12453816724761706, 112907775890596400, 1027394297869071687

Offset: 0

Author

Seiichi Manyama, Nov 03 2023

Keywords

• nonn

Crossrefs

Cf. A176697, A367040.

Cf. A365178, A365180, A365181, A365182, A365183, A367048, A367049, A367050.

Programs

PARI

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

Formula

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