Primes of the form 2^t-2^k-1, k>=1.

Terms

a(0) =3a(1) =5a(2) =7a(3) =11a(4) =13a(5) =23a(6) =29a(7) =31a(8) =47a(9) =59a(10) =61a(11) =127a(12) =191a(13) =223a(14) =239a(15) =251a(16) =383a(17) =479a(18) =503a(19) =509a(20) =991a(21) =1019a(22) =1021a(23) =2039a(24) =3583a(25) =3967a(26) =4079a(27) =4091a(28) =4093a(29) =6143