OFFSET
0,3
FORMULA
If g.f. satisfies A(x) = ( 1 + x*A(x)^2 / (1 - x*A(x))^s )^t, then a(n) = Sum_{k=0..n} binomial(t*(n+k+1),k) * binomial(n+(s-1)*k-1,n-k)/(n+k+1).
G.f.: (1/x) * Series_Reversion( x*(1 - x/(1 - x)^3) ). - _ Seiichi Manyama_, Sep 24 2024
PROG
(PARI) a(n, s=3, t=1) = sum(k=0, n, binomial(t*(n+k+1), k)*binomial(n+(s-1)*k-1, n-k)/(n+k+1));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Aug 23 2023
STATUS
approved