a(n) = (n! - 8)/8.

Terms

a(0) =2a(1) =14a(2) =89a(3) =629a(4) =5039a(5) =45359a(6) =453599a(7) =4989599a(8) =59875199a(9) =778377599a(10) =10897286399a(11) =163459295999