The Gauss factorial n_11!.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =24a(5) =120a(6) =720a(7) =5040a(8) =40320a(9) =362880a(10) =3628800a(11) =3628800a(12) =43545600a(13) =566092800a(14) =7925299200a(15) =118879488000