A379997 Expansion of e.g.f. 1/(exp(x) - x*exp(2*x))^2.

1, 0, 6, 22, 224, 2138, 25732, 351846, 5458224, 94441042, 1803255404, 37652268014, 853321021192, 20858236815258, 546941712302052, 15313467390967222, 455933682027961184, 14383416438784605602, 479254037890010238172, 16817855455956128823486, 619953003446894086537656

Offset: 0

Author

Seiichi Manyama, Jan 07 2025

Keywords

• nonn
• easy

Crossrefs

Cf. A358738, A377529, A379933, A379992.

Cf. A092148.

Programs

PARI

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

Formula

E.g.f.: B(x)^2, where B(x) is the e.g.f. of A092148.

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