Numbers k such that 271*2^k-1 is prime.

Terms

a(0) =1a(1) =7a(2) =21a(3) =55a(4) =175a(5) =235a(6) =2289a(7) =12419a(8) =19917a(9) =19971a(10) =21979a(11) =54007a(12) =66241a(13) =68757a(14) =98595a(15) =241211a(16) =274509a(17) =322971a(18) =342349a(19) =470529