A380718 E.g.f. A(x) satisfies A(x) = exp(x * A(x)^2) / (1 - x*A(x)).
1, 2, 17, 277, 6809, 225381, 9408745, 474835159, 28128322801, 1913917635433, 147124118481641, 12610993501595523, 1192699876840875529, 123380247466574450509, 13858619936380747514953, 1679795510876270598645631, 218541202774350975212752865, 30376105717226232363041309265
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Keywords
Programs
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PARI
a(n) = n!*sum(k=0, n, (n+k+1)^(k-1)*binomial(2*n, n-k)/k!);
Formula
a(n) = n! * Sum_{k=0..n} (n+k+1)^(k-1) * binomial(2*n,n-k)/k!.