Isolated primes p such that 2^p-1 is also a prime number.

Terms

a(0) =2a(1) =89a(2) =127a(3) =607a(4) =2203a(5) =2281a(6) =3217a(7) =4253a(8) =9689a(9) =9941a(10) =11213a(11) =19937a(12) =21701a(13) =23209a(14) =44497a(15) =86243a(16) =216091a(17) =756839a(18) =859433a(19) =1257787a(20) =1398269a(21) =2976221a(22) =3021377a(23) =6972593a(24) =13466917a(25) =25964951a(26) =30402457a(27) =32582657a(28) =37156667a(29) =42643801