A377632 E.g.f. satisfies A(x) = 1/(1 - x * A(x)^2 * exp(x*A(x)^2))^2.

1, 2, 26, 666, 26000, 1372650, 91594812, 7398109838, 701939170256, 76538939053842, 9432015136260500, 1296420805666136502, 196648127058577395192, 32631136680788714502746, 5880120898119055583177756, 1143520026572037679360951710, 238712613798193658499743637152

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 A377631.

a(n) = 2 * n! * Sum_{k=0..n} k^(n-k) * binomial(4*n+k+2,k)/( (4*n+k+2)*(n-k)! ).

Prog

(PARI) a(n) = 2*n!*sum(k=0, n, k^(n-k)*binomial(4*n+k+2, k)/((4*n+k+2)*(n-k)!));

Crossrefs

Cf. A377629, A377631.

Sequence in context: A302719 A377527 A377547 * A090247 A371296 A373869

Adjacent sequences: A377629 A377630 A377631 * A377633 A377634 A377635

Keyword

nonn

Author

Seiichi Manyama, Nov 02 2024

Status

approved