OFFSET
0,9
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..400
I. Mezo, Periodicity of the last digits of some combinatorial sequences, arXiv preprint arXiv:1308.1637 [math.CO], 2013.
FORMULA
E.g.f.: 1/(2 + x - exp(x) + x^2/2 + x^3/6). - Vaclav Kotesovec, Aug 02 2014
a(n) ~ n! / ((1+r^3/6) * r^(n+1)), where r = 1.97615974210650519398... is the root of the equation 2 + r - exp(r) + r^2/2 + r^3/6 = 0. - Vaclav Kotesovec, Aug 02 2014
a(0) = 1; a(n) = Sum_{k=4..n} binomial(n,k) * a(n-k). - Ilya Gutkovskiy, Feb 09 2020
MAPLE
b:= proc(n) b(n):= `if`(n=0, 1, add(b(n-j)/j!, j=4..n)) end:
a:= n-> n!*b(n):
seq(a(n), n=0..30); # Alois P. Heinz, Jul 29 2014
MATHEMATICA
CoefficientList[Series[1/(2 + x - E^x + x^2/2 + x^3/6), {x, 0, 20}], x]*Range[0, 20]! (* Vaclav Kotesovec, Aug 02 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 27 2013
EXTENSIONS
More terms from Alois P. Heinz, Jul 29 2014
STATUS
approved