Mersenne exponents: primes p such that 2^p - 1 is prime. Then 2^p - 1 is called a Mersenne prime.

Terms

a(0) =2a(1) =3a(2) =5a(3) =7a(4) =13a(5) =17a(6) =19a(7) =31a(8) =61a(9) =89a(10) =107a(11) =127a(12) =521a(13) =607a(14) =1279a(15) =2203a(16) =2281a(17) =3217a(18) =4253a(19) =4423a(20) =9689a(21) =9941a(22) =11213a(23) =19937a(24) =21701a(25) =23209a(26) =44497a(27) =86243a(28) =110503a(29) =132049