The Gauss factorial n_7!.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =24a(5) =120a(6) =720a(7) =720a(8) =5760a(9) =51840a(10) =518400a(11) =5702400a(12) =68428800a(13) =889574400a(14) =889574400a(15) =13343616000a(16) =213497856000