A379661 Expansion of e.g.f. (1/x) * Series_Reversion( x * (exp(-2*x) - x) ).
1, 3, 32, 638, 18992, 757152, 37946944, 2294428880, 162614380544, 13224995258624, 1214230905887744, 124244350629669888, 14021254268885487616, 1730161184870597414912, 231756218205467830255616, 33492293939832097344370688, 5194237715163522538324557824, 860510764365813120075516739584
Offset: 0
Keywords
Programs
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PARI
a(n) = n!*sum(k=0, n, 2^k*(2*n-k+1)^(k-1)*binomial(2*n-k+1, n-k)/k!);
Formula
a(n) = n! * Sum_{k=0..n} 2^k * (2*n-k+1)^(k-1) * binomial(2*n-k+1,n-k)/k!.