OFFSET
0,3
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..451
FORMULA
a(n) = n! * Sum_{k=0..n-1} (-2)^k / ((n-k) * k!).
a(n) = Sum_{k=0..n} (-1)^(n-k) * binomial(n,k) * A002741(k).
a(0) = 0, a(1) = 1, a(n) = (n-3) * a(n-1) + 2 * (n-1) * a(n-2) + (-2)^(n-1). - Seiichi Manyama, May 27 2022
a(n) ~ exp(-2) * (n-1)!. - Vaclav Kotesovec, Jun 08 2022
MATHEMATICA
nmax = 24; CoefficientList[Series[-Log[1 - x] Exp[-2 x], {x, 0, nmax}], x] Range[0, nmax]!
Table[n! Sum[(-2)^k/((n - k) k!), {k, 0, n - 1}], {n, 0, 24}]
PROG
(PARI) a_vector(n) = my(v=vector(n+1)); v[1]=0; v[2]=1; for(i=2, n, v[i+1]=(i-3)*v[i]+2*(i-1)*v[i-1]+(-2)^(i-1)); v; \\ Seiichi Manyama, May 27 2022
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Jul 15 2021
STATUS
approved