Least prime power > 2^n.

Terms

a(0) =2a(1) =3a(2) =5a(3) =9a(4) =17a(5) =37a(6) =67a(7) =131a(8) =257a(9) =521a(10) =1031a(11) =2053a(12) =4099a(13) =8209a(14) =16411a(15) =32771a(16) =65537a(17) =131101a(18) =262147a(19) =524309a(20) =1048583a(21) =2097169a(22) =4194319a(23) =8388617a(24) =16777259a(25) =33554467a(26) =67108879a(27) =134217757a(28) =268435459a(29) =536870923