A362274 Expansion of e.g.f. 1/(1-x*exp(x*exp(x))).
1, 1, 4, 27, 232, 2465, 31416, 467173, 7940080, 151824177, 3225664720, 75386002901, 1921987809336, 53085088574713, 1578989028324904, 50320957240554645, 1710595789688360416, 61783832256587799137, 2362794061464082513440, 95380148553556615501717
Offset: 0
Keywords
Links
- Winston de Greef, Table of n, a(n) for n = 0..398
Programs
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PARI
my(N=20, x='x+O('x^N)); Vec(serlaplace(1/(1-x*exp(x*exp(x)))))
Formula
a(n) = n! * Sum_{i=0..n} Sum_{j=0..n-i} i^j * j^(n-i-j) / (j! * (n-i-j)!).