a(n) = 1^n + 2^(n+1) + 3^(n+2).

Terms

a(0) =5a(1) =12a(2) =32a(3) =90a(4) =260a(5) =762a(6) =2252a(7) =6690a(8) =19940a(9) =59562a(10) =178172a(11) =533490a(12) =1598420a(13) =4791162a(14) =14365292a(15) =43079490a(16) =129205700a(17) =387551562a(18) =1162523612a(19) =3487308690a(20) =10461401780a(21) =31383156762a(22) =94147373132a(23) =282437925090a(24) =847305386660