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A362349
a(n) = n! * Sum_{k=0..floor(n/4)} k^k / (k! * (n-4*k)!).
5
1, 1, 1, 1, 25, 121, 361, 841, 82321, 728785, 3633841, 13313521, 2195435881, 28125394441, 196393341145, 981274727161, 227100486456481, 3807339471993121, 34186011461595361, 216366574074187105, 64438384450412161081, 1335035336388170601241
OFFSET
0,5
LINKS
Eric Weisstein's World of Mathematics, Lambert W-Function.
FORMULA
E.g.f.: exp(x) / (1 + LambertW(-x^4)).
PROG
(PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x)/(1+lambertw(-x^4))))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Apr 17 2023
STATUS
approved