(n-1)!/n or 0 if n does not divide (n-1)!.

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =0a(5) =20a(6) =0a(7) =630a(8) =4480a(9) =36288a(10) =0a(11) =3326400a(12) =0a(13) =444787200a(14) =5811886080a(15) =81729648000a(16) =0a(18) =0a(22) =0