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

Terms

a(0) =5a(1) =10a(2) =17a(3) =28a(4) =47a(5) =82a(6) =149a(7) =280a(8) =539a(9) =1054a(10) =2081a(11) =4132a(12) =8231a(13) =16426a(14) =32813a(15) =65584a(16) =131123a(17) =262198a(18) =524345a(19) =1048636a(20) =2097215a(21) =4194370a(22) =8388677a(23) =16777288a(24) =33554507a(25) =67108942a(26) =134217809a(27) =268435540a(28) =536870999a(29) =1073741914