a(n) = 1^n + 8^n + 9^n.

Terms

a(0) =3a(1) =18a(2) =146a(3) =1242a(4) =10658a(5) =91818a(6) =793586a(7) =6880122a(8) =59823938a(9) =521638218a(10) =4560526226a(11) =39970994202a(12) =351149013218