a(n+1) = n*a(n) - (-1)^n.

Terms

a(0) =1a(1) =2a(2) =3a(3) =10a(4) =39a(5) =196a(6) =1175a(7) =8226a(8) =65807a(9) =592264a(10) =5922639a(11) =65149030a(12) =781788359a(13) =10163248668a(14) =142285481351