A380719 E.g.f. A(x) satisfies A(x) = exp(x / (1 - x*A(x))^2) / (1 - x*A(x)).
1, 2, 13, 157, 2817, 67541, 2033293, 73793399, 3137724033, 153046171657, 8425546124661, 516854537135795, 34963627698674689, 2585888583437930525, 207593192181190597629, 17978635157682679541311, 1670861912137958623651329, 165868047783912942721097873, 17517226956387964424430057829
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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!.