OFFSET
0,2
LINKS
Eric Weisstein's World of Mathematics, Lambert W-Function.
FORMULA
E.g.f.: 1/(1 + LambertW( 2 * (1 - exp(x)) )), where LambertW() is the Lambert W-function.
a(n) ~ n^n / (sqrt(1 + 2*exp(1)) * (log(exp(1) + 1/2) - 1)^(n + 1/2) * exp(n)). - Vaclav Kotesovec, Feb 06 2022
PROG
(PARI) a(n) = sum(k=0, n, (2*k)^k*stirling(n, k, 2));
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(1/(1+lambertw(2*(1-exp(x))))))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Feb 05 2022
STATUS
approved