A377489 E.g.f. satisfies A(x) = 1/(1 - A(x)^2 * (exp(x) - 1))^2.

1, 2, 24, 548, 18996, 889532, 52623924, 3767367788, 316781141316, 30608709436412, 3342279339791124, 407043376061484428, 54704971792071412836, 8042679084840031176092, 1284038419974274852278324, 221234151594672691543079468, 40916180234895561309469607556

Offset: 0

Author

Seiichi Manyama, Oct 29 2024

Keywords

• nonn

Crossrefs

Cf. A377451, A377454.

Programs

PARI

a(n) = 2*sum(k=0, n, (5*k+1)!/(4*k+2)!*stirling(n, k, 2));

Formula

E.g.f.: B(x)^2, where B(x) is the e.g.f. of A377451.

a(n) = 2 * Sum_{k=0..n} (5*k+1)!/(4*k+2)! * Stirling2(n,k).