a(n) = 12^n - n^5.

Terms

a(0) =1a(1) =11a(2) =112a(3) =1485a(4) =19712a(5) =245707a(6) =2978208a(7) =35815001a(8) =429948928a(9) =5159721303a(10) =61917264224a(11) =743008209637