OFFSET
0,2
FORMULA
E.g.f.: A(x) = B(x)^2 where B(x) is the e.g.f. of A138860.
If e.g.f. satisfies A(x) = exp( r*x*A(x)^(t/r) * (1 + A(x)^(u/r)) ), then a(n) = r * Sum_{k=0..n} (t*n+u*k+r)^(n-1) * binomial(n,k).
PROG
(PARI) a(n, r=1, t=1/2, u=1/2) = r*sum(k=0, n, (t*n+u*k+r)^(n-1)*binomial(n, k));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Apr 23 2024
STATUS
approved