A054131 T(2n,n), array T as in A054126.

2, 5, 24, 134, 802, 4960, 31212, 198504, 1271754, 8192780, 53009614, 344213930, 2241814696, 14637778784, 95786210880

Offset: 0

Author

Clark Kimberling

Keywords

• nonn

Crossrefs

Cf. A054126.

Programs

PARI

a(n) = if(n==0, 2, 2^(n-1) + sum(m=0, n, binomial(3*n,m))) \\ Jianing Song, May 30 2022

Formula

a(n) = A052509(4*n,3*n+1) + A052509(4*n,n) = 2^(n-1) + Sum_{m=0..n} binomial(3*n,m). for n >= 1. - Jianing Song, May 30 2022