Primes p such that 2^p-1 is prime and congruent to 31 mod 5!.

Terms

a(0) =5a(1) =13a(2) =17a(3) =61a(4) =89a(5) =521a(6) =2281a(7) =3217a(8) =4253a(9) =9689a(10) =9941a(11) =11213a(12) =19937a(13) =21701a(14) =23209a(15) =44497a(16) =132049a(17) =859433a(18) =1398269a(19) =2976221a(20) =3021377a(21) =6972593a(22) =13466917a(23) =30402457a(24) =32582657a(25) =42643801a(26) =43112609a(27) =57885161