Primes of the form q*2^h + 1, where q is a Mersenne prime.

Terms

a(0) =7a(1) =13a(2) =29a(3) =97a(4) =113a(5) =193a(6) =449a(7) =509a(8) =769a(9) =7937a(10) =12289a(11) =114689a(12) =520193a(13) =786433a(14) =7340033a(15) =8388593a(16) =33292289a(17) =33550337a(18) =469762049a(19) =2130706433a(20) =3221225473a(21) =8588886017a(22) =137438691329a(23) =206158430209