Numbers k such that 31*2^k-1 is prime.

Terms

a(0) =1a(1) =5a(2) =7a(3) =11a(4) =13a(5) =23a(6) =33a(7) =35a(8) =37a(9) =47a(10) =115a(11) =205a(12) =235a(13) =271a(14) =409a(15) =739a(16) =837a(17) =887a(18) =2189a(19) =3465a(20) =4653a(21) =5073a(22) =8011a(23) =8061a(24) =21957a(25) =24589a(26) =25657a(27) =44653a(28) =50321a(29) =57647