a(n) = (1/4)*(n^2 - 5*n + 2)*(n-2)! + 1.

Terms

a(0) =0a(1) =0a(2) =0a(3) =4a(4) =49a(5) =481a(6) =4681a(7) =47881a(8) =524161a(9) =6168961a(10) =78019201a(11) =1057795201a(12) =15328051201a(13) =236626790401