A368268 Expansion of e.g.f. exp(-x) / (1 - 2*x*exp(x)).

1, 1, 9, 71, 817, 11599, 197881, 3938087, 89569761, 2291869727, 65159228521, 2037767466679, 69521938950289, 2569515452879855, 102274007835523161, 4361566914028222919, 198403133940750790081, 9589223805173365594687, 490729273233730201604809

Offset: 0

Author

Seiichi Manyama, Dec 19 2023

Keywords

• nonn
• easy

Crossrefs

Cf. A351762, A368236, A368267, A368269.

Programs

PARI

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

Formula

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