a(n) = 7^n + 5^n - 3^n - 2^n.

Terms

a(0) =0a(1) =7a(2) =61a(3) =433a(4) =2929a(5) =19657a(6) =132481a(7) =899353a(8) =6148609a(9) =42286537a(10) =292180801a(11) =2025975673a(12) =14084892289a(13) =98108111017a(14) =684321789121