A380752 E.g.f. A(x) satisfies A(x) = exp(x * A(x)) / (1 - x * A(x)^2)^2.
1, 3, 41, 1114, 46217, 2595186, 184264033, 15839938318, 1599772132337, 185698542344050, 24362771800087241, 3565209717372983142, 575786158331135496313, 101729690893078619387914, 19518889966696995273600209, 4041785999884112498658681406, 898403694387449768732923267937
Offset: 0
Keywords
Programs
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PARI
a(n) = n!*sum(k=0, n, (2*n-k+1)^(k-1)*binomial(5*n-3*k+1, n-k)/k!);
Formula
a(n) = n! * Sum_{k=0..n} (2*n-k+1)^(k-1) * binomial(5*n-3*k+1,n-k)/k!.