a(n) is the smallest prime p which is greater than the exponent of the n-th Mersenne prime.

Terms

a(0) =3a(1) =5a(2) =7a(3) =11a(4) =17a(5) =19a(6) =23a(7) =37a(8) =67a(9) =97a(10) =109a(11) =131a(12) =523a(13) =613a(14) =1283a(15) =2207a(16) =2287a(17) =3221a(18) =4259a(19) =4441a(20) =9697a(21) =9949a(22) =11239a(23) =19949a(24) =21713a(25) =23227a(26) =44501a(27) =86249a(28) =110527a(29) =132059