OFFSET
0,2
FORMULA
E.g.f.: B(x)^2, where B(x) is the e.g.f. of A367135.
a(n) = (2/(3*n+2)!) * Sum_{k=0..n} (3*n+k+1)! * Stirling2(n,k).
PROG
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace((serreverse(x*(2-exp(x))^3)/x)^(2/3)))
(PARI) a(n) = 2*sum(k=0, n, (3*n+k+1)!*stirling(n, k, 2))/(3*n+2)!;
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Sep 22 2024
STATUS
approved