a(n) = 1^n + 3^n + 5^n.

Terms

a(0) =3a(1) =9a(2) =35a(3) =153a(4) =707a(5) =3369a(6) =16355a(7) =80313a(8) =397187a(9) =1972809a(10) =9824675a(11) =49005273a(12) =244672067a(13) =1222297449a(14) =6108298595a(15) =30531927033a(16) =152630937347a(17) =763068593289