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A358080

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

1, 0, 2, 6, 36, 260, 2190, 21882, 248696, 3181320, 45229050, 707208590, 12063902532, 222939837276, 4436813677478, 94605994108290, 2151763873634160, 51999544476324752, 1330540380342907506, 35936656483848501654, 1021700660649312689660

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..425

FORMULA

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

a(n) ~ n! / ((1 + LambertW(1/2)) * 2^(n+1) * LambertW(1/2)^n). - Vaclav Kotesovec, Oct 30 2022

PROG

(PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(1-x^2*exp(x))))

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

CROSSREFS

Cf. A006153, A358081.

Cf. A216507, A345747, A358064.

Sequence in context: A060178 A096939 A351825 * A369091 A162697 A377533

Adjacent sequences: A358077 A358078 A358079 * A358081 A358082 A358083

KEYWORD

nonn,easy

AUTHOR

Seiichi Manyama, Oct 30 2022

STATUS

approved

URL: https://oeis.org/A358080

⇱ A358080 - OEIS