A367163 E.g.f. satisfies A(x) = 1 + A(x)^3 * (exp(x*A(x)) - 1).
1, 1, 9, 160, 4367, 161796, 7592593, 431826760, 28875060411, 2220199609420, 193010401410437, 18720726373805952, 2004328775014537111, 234797380878372574276, 29873926565253226992921, 4102473564838214815027576, 604804589755948599369229811
Offset: 0
Keywords
Programs
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PARI
a(n) = sum(k=0, n, (n+3*k)!/(n+2*k+1)!*stirling(n, k, 2));
Formula
a(n) = Sum_{k=0..n} (n+3*k)!/(n+2*k+1)! * Stirling2(n,k).