A369783 Expansion of e.g.f. exp( exp(3*(exp(x)-1))-1 ).
1, 3, 21, 192, 2154, 28434, 429213, 7261788, 135698268, 2769463335, 61186736415, 1452889463034, 36857766745749, 993941679586098, 28370018078000985, 853903169641805925, 27014392815958815969, 895723118730738795837, 31048284069527339602902
Offset: 0
Keywords
Programs
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PARI
my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(exp(3*(exp(x)-1))-1)))
Formula
a(n) = Sum_{k=0..n} 3^k * Stirling2(n,k) * Bell(k) = Sum_{k=0..n} Stirling2(n,k) * A247452(k).