A377547 E.g.f. satisfies A(x) = 1/(1 - x * A(x)^2 * exp(x*A(x)))^2.

1, 2, 26, 642, 24032, 1213770, 77394732, 5969555438, 540660333488, 56259187813170, 6614835933664820, 867369682746517302, 125500890673265913192, 19863391924198865128970, 3413850970930399074000044, 633165846392393276109473790, 126051163243470714005823101792

Offset

0,2

Links

Table of n, a(n) for n=0..16.

Formula

E.g.f.: B(x)^2, where B(x) is the e.g.f. of A377549.

a(n) = 2 * n! * Sum_{k=0..n} k^(n-k) * binomial(2*n+3*k+2,k)/( (2*n+3*k+2)*(n-k)! ).

Prog

(PARI) a(n) = 2*n!*sum(k=0, n, k^(n-k)*binomial(2*n+3*k+2, k)/((2*n+3*k+2)*(n-k)!));

Crossrefs

Cf. A377549.

Sequence in context: A255538 A302719 A377527 * A377632 A090247 A371296

Adjacent sequences: A377544 A377545 A377546 * A377548 A377549 A377550

Keyword

nonn

Author

Seiichi Manyama, Oct 31 2024

Status

approved