a(n) = n!*n*(n-1)*(n-2)/36.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =16a(5) =200a(6) =2400a(7) =29400a(8) =376320a(9) =5080320a(10) =72576000a(11) =1097712000a(12) =17563392000a(13) =296821324800