a(n) = 5^n - 3^n - 2^n.

Terms

a(0) =-1a(1) =0a(2) =12a(3) =90a(4) =528a(5) =2850a(6) =14832a(7) =75810a(8) =383808a(9) =1932930a(10) =9705552a(11) =48648930a(12) =243605088a(13) =1219100610a(14) =6098716272a(15) =30503196450a(16) =152544778368a(17) =762810181890