Numbers of the form 2^k+3 or 3*2^k+1, k >= 2.

Terms

a(0) =7a(1) =11a(2) =13a(3) =19a(4) =25a(5) =35a(6) =49a(7) =67a(8) =97a(9) =131a(10) =193a(11) =259a(12) =385a(13) =515a(14) =769a(15) =1027a(16) =1537a(17) =2051a(18) =3073a(19) =4099a(20) =6145a(21) =8195a(22) =12289a(23) =16387a(24) =24577a(25) =32771a(26) =49153a(27) =65539a(28) =98305a(29) =131075