OFFSET
2,2
PROG
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(log(1+log(1+log(1+log(1+log(1+x)))))^2/2))
(PARI) T(n, k) = if(k==0, n==1, sum(j=0, n, abs(stirling(n, j, 1))*T(j, k-1)));
a(n) = (-1)^n*sum(k=1, n-1, binomial(n-1, k)*T(k, 5)*T(n-k, 5));
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Feb 13 2022
STATUS
approved