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

Terms

a(0) =0a(1) =1a(2) =-2a(3) =6a(4) =0a(5) =-120a(6) =1440a(7) =-10080a(8) =40320a(9) =362880a(10) =-10886400a(11) =159667200a(12) =-1437004800a(13) =0a(14) =348713164800