A364978 E.g.f. satisfies A(x) = 1 + x*exp(x*A(x)^2).

1, 1, 2, 15, 124, 1565, 23886, 446887, 9787352, 246408633, 7010910010, 222438284651, 7788393551412, 298293192119221, 12406118302851014, 556817903190669135, 26825727269937929776, 1380790608848655193457, 75625529930102546486514

Offset: 0

Author

Seiichi Manyama, Aug 15 2023

Keywords

• nonn

Crossrefs

Cf. A161631, A364979.

Programs

PARI

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

Formula

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