A371317 E.g.f. satisfies A(x) = (exp(x) - 1)/(1 - A(x))^3.
0, 1, 7, 109, 2767, 97621, 4411927, 243200749, 15823364767, 1186906701061, 100841639699047, 9571637343623389, 1003836707927846767, 115277656980955696501, 14386616557957088368567, 1938794142849968447054029, 280599557966128999505000767
Offset: 0
Keywords
Programs
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PARI
a(n) = sum(k=1, n, (4*k-2)!/(3*k-1)!*stirling(n, k, 2));
Formula
a(n) = Sum_{k=1..n} (4*k-2)!/(3*k-1)! * Stirling2(n,k).
E.g.f.: Series_Reversion( log(1 + x * (1 - x)^3) ). - Seiichi Manyama, Sep 08 2024