a(n) = 2^n + 5.

Terms

a(0) =6a(1) =7a(2) =9a(3) =13a(4) =21a(5) =37a(6) =69a(7) =133a(8) =261a(9) =517a(10) =1029a(11) =2053a(12) =4101a(13) =8197a(14) =16389a(15) =32773a(16) =65541a(17) =131077a(18) =262149a(19) =524293a(20) =1048581a(21) =2097157a(22) =4194309a(23) =8388613a(24) =16777221a(25) =33554437a(26) =67108869a(27) =134217733a(28) =268435461a(29) =536870917