a(n) = 11^n - n^4.

Terms

a(0) =1a(1) =10a(2) =105a(3) =1250a(4) =14385a(5) =160426a(6) =1770265a(7) =19484770a(8) =214354785a(9) =2357941130a(10) =25937414601a(11) =285311655970