A368273 Expansion of e.g.f. exp(-2*x) / (1 + x*exp(x)).

1, -3, 8, -17, 20, 23, -50, -1185, 6648, 20143, -372646, 179111, 25378468, -126050121, -1849977930, 23353880527, 109161798512, -3986970251809, 6487865966386, 680166849412311, -5885809282265124, -109572316727641433, 2250978116175344846, 11909910338327490623

Offset: 0

Author

Seiichi Manyama, Dec 19 2023

Keywords

• sign

Crossrefs

Cf. A302397, A368271, A368272.

Programs

PARI

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

Formula

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