OFFSET
0,4
FORMULA
a(n) = 2 * Sum_{k=0..floor(n/2)} (-1)^k * (1-4^k) * |Stirling1(n,2*k)| * Bernoulli(2*k).
a(n) ~ n! * 2*Pi / (exp(Pi) * (1 - exp(-Pi))^(n+1)). - Vaclav Kotesovec, Oct 05 2022
PROG
(PARI) my(N=30, x='x+O('x^N)); concat([0, 0], Vec(serlaplace(log(1-x)*tan(log(1-x)/2))))
(PARI) a(n) = 2*sum(k=0, n\2, (-1)^k*(1-4^k)*abs(stirling(n, 2*k, 1))*bernfrac(2*k));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 05 2022
STATUS
approved