a(n) = 8^n + 8*n.

Terms

a(0) =1a(1) =16a(2) =80a(3) =536a(4) =4128a(5) =32808a(6) =262192a(7) =2097208a(8) =16777280a(9) =134217800a(10) =1073741904a(11) =8589934680a(12) =68719476832a(13) =549755813992