A379886 E.g.f. A(x) satisfies A(x) = 1/(exp(-x) - x*A(x)^2).

1, 2, 15, 247, 6221, 212421, 9181555, 480780875, 29589829785, 2093629793113, 167458531710431, 14942213260220247, 1471585837443194533, 158562898380718019813, 18555214181719160291403, 2343490814996151816116131, 317730224718816177328965425, 46028095309438150072340711601

Offset: 0

Author

Seiichi Manyama, Jan 05 2025

Keywords

• nonn

Crossrefs

Cf. A377891, A377893, A379867.

Programs

PARI

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

Formula

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