A379026 a(n) = Sum_{k=0..n} binomial(4*n+k-1,k) * binomial(4*n+k,n-k).

1, 8, 136, 2612, 52888, 1103248, 23458756, 505519792, 11001461560, 241240165796, 5321735043496, 117969960106380, 2625673485660100, 58638653062716488, 1313363972969179904, 29489827322243843032, 663600214363813934328, 14961465721142755457484

Offset: 0

Author

Seiichi Manyama, Dec 14 2024

Keywords

• nonn

Crossrefs

Cf. A262910, A379022, A379025.

Cf. A379024.

Programs

PARI

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

Formula

a(n) = [x^n] ( (1 + x)/(1 - x - x^2) )^(4*n).