A372250 E.g.f. A(x) satisfies A(x) = exp( x * A(x) * (1 + x^2 * A(x)) ).
1, 1, 3, 22, 221, 2796, 44527, 857074, 19250457, 494672824, 14331709691, 462277166814, 16430392693717, 638087135544340, 26885810437578471, 1221643263680551786, 59548603124180235953, 3099741728641090867056, 171619335190080336331891
Offset: 0
Keywords
Links
- Seiichi Manyama, Table of n, a(n) for n = 0..376
Programs
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PARI
a(n) = n!*sum(k=0, n\3, (n-k+1)^(n-2*k-1)/(k!*(n-3*k)!));
Formula
a(n) = n! * Sum_{k=0..floor(n/3)} (n-k+1)^(n-2*k-1) / (k! * (n-3*k)!).