OFFSET
0,2
FORMULA
Let r = [4,...,4] (n occurrences of 4), s = [1,...,1,2] (n-1 occurrences of 1)
and F_n the generalized hypergeometric function of type n_F_n, then
a(n) = exp(-1)*3!^n*F_n(r,s |1).
e.g.f.: Sum_{j>=0}(exp((j+2)!/(j-1)!*x-1)/j!).
MAPLE
MATHEMATICA
a[n_] := 3!^n*HypergeometricPFQ[ Table[4, {n}], Append[ Table[1, {n-1}], 2], 1.`40.]/E; Table[Round[a[n]], {n, 0, 12}] (* Jean-François Alcover, Jul 29 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, Mar 29 2011
STATUS
approved