A379688 Expansion of e.g.f. (1/x) * Series_Reversion( x * (1 - 2*x*exp(x)) ).
1, 2, 20, 366, 9992, 365130, 16769292, 929022206, 60323670416, 4494465562770, 378025706776340, 35434198578761862, 3663111561838580568, 414057463231218044186, 50805545997014472821276, 6725525908390393438264590, 955435863749903677193184032, 144987884255349864723586105122
Offset: 0
Keywords
Links
- Seiichi Manyama, Table of n, a(n) for n = 0..326
Programs
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PARI
a(n) = sum(k=0, n, 2^(n-k)*(n-k)^k*(2*n-k)!/(k!*(n-k)!))/(n+1);
Formula
a(n) = (1/(n+1)) * Sum_{k=0..n} 2^(n-k) * (n-k)^k * (2*n-k)!/(k! * (n-k)!).
E.g.f. A(x) satisfies A(x) = 1/( 1 - 2*x*A(x)*exp(x*A(x)) ).
E.g.f.: B(x)^2, where B(x) is the e.g.f. of A380095.