A365124 G.f. satisfies A(x) = (1 + x / (1 - x*A(x))^4)^4.
1, 4, 22, 156, 1209, 10020, 86724, 775044, 7096652, 66232980, 627749066, 6025752664, 58459917618, 572315274540, 5646713239840, 56091780016288, 560513824012020, 5630664768126388, 56829055796539462, 575981263878482204, 5859952654335118851
Offset: 0
Keywords
Programs
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PARI
a(n, s=4, t=4) = sum(k=0, n, binomial(t*(n-k+1), k)*binomial(n+(s-1)*k-1, n-k)/(n-k+1));
Formula
If g.f. satisfies A(x) = (1 + x/(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).