A316090 a(n) = [x^n] (Sum_{k=0..n} (k*x)^k)/(Sum_{k=0..n} (-k*x)^k).
1, 2, 2, 48, 94, 5694, 12352, 1539850, 3323890, 737028224, 1556371198, 548747031342, 1138137849328, 586694732526026, 1202647898994626, 852409708509446800, 1734703213512100766, 1616070775292699964094, 3273912763003648926368, 3875483980992048140938410
Offset: 0
Keywords
Links
- Seiichi Manyama, Table of n, a(n) for n = 0..386
Programs
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PARI
N=66; x='x+O('x^N); Vec((sum(k=0, N, (k*x)^k))/(sum(k=0, N, (-k*x)^k)))
Formula
a(n) ~ 4 * exp(-1) * n^(n-1) if n is even and a(n) ~ 2 * n^n if n is odd. - Vaclav Kotesovec, Jun 25 2018