%I #8 Oct 14 2016 11:31:22
%S 2,3,40,105,1584,5985,107136,530145,11116800,68139225,1644364800,
%T 12034447425,329001523200,2801155982625,85619242598400,
%U 831764543234625,28117244819865600,307025061241523625,11374945402060800000
%N a(n) = (n!!)^2 - n!.
%F E.g.f.: x*(1 - sqrt(1 - x^2) + arcsin(x))/(1 - x^2)^(3/2). - _Benedict W. J. Irwin_, Oct 14 2016
%t Table[CoefficientList[Series[(x(1-Sqrt[1-x^2]+ArcSin[x]))/(1-x^2)^(3/2), {x, 0, 20}], x][[n]](n-1)!, {n, 3, 20}] (* _Benedict W. J. Irwin_, Oct 14 2016 *)
%K nonn
%O 2,1
%A _Vladeta Jovovic_, Oct 31 2003