OFFSET
0,5
FORMULA
a(n) = n! * Sum_{k=0..floor(n/2)} (-1)^k/k!.
PROG
(PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(-x^2)/(1-x)))
(PARI) a(n) = n!*sum(k=0, n\2, (-1)^k/k!);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Feb 27 2024
STATUS
approved