a(n) = 12^n - n^12.

Terms

a(0) =1a(1) =11a(2) =-3952a(3) =-529713a(4) =-16756480a(5) =-243891793a(6) =-2173796352a(7) =-13805455393a(8) =-68289495040a(9) =-277269756129a(10) =-938082635776a(12) =0