a(n) = n! * [x^n] (1 - x)^(n*x).

Terms

a(0) =1a(1) =0a(2) =-4a(3) =-9a(4) =160a(5) =1350a(6) =-14904a(7) =-335160a(8) =1796096a(9) =125615448a(10) =204300000a(11) =-64591072920a(12) =-735003528192