A379285 G.f. A(x) satisfies A(x) = 1/((1 - x*A(x)^2) * (1 - x*A(x)^3)).

1, 2, 13, 115, 1175, 13052, 153115, 1866599, 23414063, 300238945, 3917984904, 51862207151, 694670871393, 9398137507922, 128235826442635, 1762706644013297, 24386388751113511, 339295523459625535, 4744546261930628062, 66644485202547680010, 939916204595095866644

Offset: 0

Author

Seiichi Manyama, Dec 19 2024

Keywords

• nonn

Crossrefs

Cf. A118969, A199475, A379209, A379284, A379286, A379287.

Programs

PARI

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

Formula

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