A303565 a(n) = [x^n] (Sum_{k=0..n} k!*x^k)/(Sum_{k=0..n} k!*(-x)^k).

1, 2, 2, 10, 18, 202, 418, 8762, 18546, 648842, 1361090, 72858394, 150831762, 11533704106, 23631529186, 2447950210490, 4980921068466, 671176131216458, 1359534955872002, 230971485534437722, 466475222145987282, 97492025362288590058, 196500782158151756578

Offset: 0

Author

Seiichi Manyama, Apr 26 2018

Keywords

• nonn

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..450

Crossrefs

Cf. A303566.

Programs

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*(n-1)! if n is even and a(n) ~ 2*n! if n is odd. - Vaclav Kotesovec, May 02 2018