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

Terms

a(0) =0a(1) =7a(2) =105a(3) =1267a(4) =14385a(5) =160027a(6) =1767465a(7) =19470787a(8) =214293345a(9) =2357685547a(10) =25936376025a(11) =285307476307