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A357948 Expansion of e.g.f. exp( x * exp(-x^2) ). 1
1, 1, 1, -5, -23, 1, 601, 2731, -13775, -219743, -313199, 15383611, 125451481, -811558175, -20767068503, -37852036949, 2898343066081, 28990920216001, -313289894357855, -8634009894555653, -3214642669500599, 2108734127922999361, 20183394611962437241 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,4
LINKS
FORMULA
a(n) = n! * Sum_{k=0..floor(n/2)} (-n + 2*k)^k/(k! * (n - 2*k)!).
PROG
(PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x*exp(-x^2))))
(PARI) a(n) = n!*sum(k=0, n\2, (-n+2*k)^k/(k!*(n-2*k)!));
CROSSREFS
Cf. A216688.
Sequence in context: A002069 A298233 A215742 * A367721 A282688 A282875
KEYWORD
sign,easy
AUTHOR
Seiichi Manyama, Oct 29 2022
STATUS
approved

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Last modified April 14 00:20 EDT 2024. Contains 371652 sequences. (Running on oeis4.)