OFFSET
0,3
FORMULA
a(n) = (-1)^n * n! * Sum_{k=0..n} 4^k * binomial((n-k)/2,k)/(n-k)!.
a(n) ~ 2^(2*n - 5/2) * n^(n-1) / exp(n). - Vaclav Kotesovec, Apr 10 2023
PROG
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(-x*sqrt(1-4*x))))
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Seiichi Manyama, Apr 10 2023
STATUS
approved