a(n) = 16^n - 15^n.

Terms

a(0) =0a(1) =1a(2) =31a(3) =721a(4) =14911a(5) =289201a(6) =5386591a(7) =97576081a(8) =1732076671a(9) =30276117361a(10) =522861237151