E.g.f. (1-x)^2/(1-2x+x^2-x^3).

Terms

a(0) =1a(1) =0a(2) =0a(3) =6a(4) =48a(5) =360a(6) =3600a(7) =45360a(8) =645120a(9) =10160640a(10) =177811200a(11) =3432844800a(12) =72329241600