a(n) = n^n - n^2 with 0^0=1.

Terms

a(0) =1a(1) =0a(2) =0a(3) =18a(4) =240a(5) =3100a(6) =46620a(7) =823494a(8) =16777152a(9) =387420408a(10) =9999999900a(11) =285311670490