Primes of the form 7*2^k-3 or 7*2^k+3.

Terms

a(0) =11a(1) =17a(2) =31a(3) =53a(4) =59a(5) =109a(6) =227a(7) =1789a(8) =3581a(9) =28669a(10) =57347a(11) =114691a(12) =229373a(13) =3670013a(14) =14680067a(15) =58720253a(16) =117440509a(17) =7516192771a(18) =60129542141