A364740 G.f. satisfies A(x) = 1 + x*A(x)^2 / (1 - x*A(x)^5).
1, 1, 3, 15, 91, 607, 4298, 31720, 241321, 1879097, 14903013, 119965086, 977623639, 8049579047, 66864689674, 559650696185, 4715304229460, 39960204165865, 340395043021399, 2912963919210012, 25031055321749916, 215894227588453950, 1868403327770467149
Offset: 0
Keywords
Programs
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PARI
a(n) = if(n==0, 1, sum(k=0, n-1, binomial(n, k)*binomial(2*n+3*k, n-1-k))/n);
Formula
a(n) = (1/n) * Sum_{k=0..n-1} binomial(n,k) * binomial(2*n+3*k,n-1-k) for n > 0.