OFFSET
0,2
FORMULA
E.g.f.: B(x)^2, where B(x) is the e.g.f. of A138013.
E.g.f.: A(x) = ( (1/x) * Series_Reversion(x / (1 - log(1-x))) )^2.
a(n) = 2 * (n+1)! * Sum_{k=0..n} |Stirling1(n,k)|/(n-k+2)!.
PROG
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace((serreverse(x/(1-log(1-x)))/x)^2))
(PARI) a(n) = 2*(n+1)!*sum(k=0, n, abs(stirling(n, k, 1))/(n-k+2)!);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Sep 02 2024
STATUS
approved