A303565 - OEIS

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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

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

LINKS

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

FORMULA

a(n) ~ 4*(n-1)! if n is even and a(n) ~ 2*n! if n is odd. - Vaclav Kotesovec, May 02 2018

PROG

(PARI) N=66; x='x+O('x^N); Vec(sum(k=0, N, k!*x^k)/sum(k=0, N, k!*(-x)^k))

CROSSREFS

Cf. A303566.

Sequence in context: A102446 A372021 A348957 * A291856 A358996 A192309

Adjacent sequences: A303562 A303563 A303564 * A303566 A303567 A303568

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Apr 26 2018

STATUS

approved