a(n) = 10^n - 4^n.

Terms

a(0) =0a(1) =6a(2) =84a(3) =936a(4) =9744a(5) =98976a(6) =995904a(7) =9983616a(8) =99934464a(9) =999737856a(10) =9998951424a(11) =99995805696a(12) =999983222784