A377892 E.g.f. A(x) satisfies A(x) = (1 + x*A(x)^2) * exp(x * A(x)^2).
1, 2, 19, 352, 9885, 374486, 17907991, 1035748260, 70334590969, 5487022612810, 483655093883451, 47541690024105608, 5156503816883562325, 611769291578643110238, 78812382009451814165695, 10956572374811382997014796, 1634950184384280878142249969, 260653481562714033459279871250
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Keywords
Programs
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PARI
a(n) = n!*sum(k=0, n, (2*n+1)^(k-1)*binomial(2*n+1, n-k)/k!);
Formula
a(n) = n! * Sum_{k=0..n} (2*n+1)^(k-1) * binomial(2*n+1,n-k)/k!.