OFFSET
0,2
FORMULA
a(n + 3) = (n + 1)^2*(n + 2)*a(n) - (5 + 3*n)*(n + 2)*a(n + 1) + (8 + 3*n)*a(n + 2). - Robert Israel, Dec 20 2018
a(n) ~ exp(-1/3 + n^(1/3)/2 + 3*n^(2/3)/2 - n) * n^(n + 1/6) / sqrt(3). - Vaclav Kotesovec, Dec 20 2018
MAPLE
egf := exp((1/(x - 1)^2 - 1)/2)/(1 - x): ser := series(egf, x, 22):
seq(n!*coeff(ser, x, n), n=0..20);
MATHEMATICA
CoefficientList[Exp[(1/(x - 1)^2 - 1)/2]/(1 - x) + O[x]^21, x] Range[0, 20]! (* Jean-François Alcover, Jan 01 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, Dec 20 2018
STATUS
approved