Numbers k such that 7*2^k - 1 is prime.

Terms

a(0) =1a(1) =5a(2) =9a(3) =17a(4) =21a(5) =29a(6) =45a(7) =177a(8) =18381a(9) =22529a(10) =24557a(11) =26109a(12) =34857a(13) =41957a(14) =67421a(15) =70209a(16) =169085a(17) =173489a(18) =177977a(19) =363929a(20) =372897