A371272 E.g.f. satisfies A(x) = 1 + x*A(x)^3 * (exp(x*A(x)^3) - 1).

1, 0, 2, 3, 148, 905, 40506, 542437, 25080392, 562677201, 28058678110, 908452740701, 49777760550684, 2120072013408505, 128583516119137730, 6778703037793746165, 455574282215526201616, 28520235381763443992993, 2118889776612629769160518

Offset: 0

Author

Seiichi Manyama, Mar 16 2024

Keywords

• nonn

Crossrefs

Cf. A371231.

Programs

PARI

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

Formula

a(n) = n! * (3*n)! * Sum_{k=0..floor(n/2)} Stirling2(n-k,k)/( (n-k)! * (3*n-k+1)! ).