A368269 Expansion of e.g.f. exp(-2*x) / (1 - 2*x*exp(x)).

1, 0, 8, 46, 584, 8138, 139252, 2770206, 63009648, 1612255186, 45837395564, 1433503025414, 48906419204392, 1807570412699322, 71946432680652324, 3068220235065662062, 139570141248903198944, 6745706553985526731682, 345212056986241161670876

Offset: 0

Author

Seiichi Manyama, Dec 19 2023

Keywords

• nonn
• easy

Crossrefs

Cf. A351762, A368236, A368267, A368268.

Programs

PARI

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

Formula

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