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

Terms

a(0) =1a(1) =2a(2) =4a(3) =5a(4) =14a(5) =24a(6) =29a(7) =36a(8) =46a(9) =80a(10) =474a(11) =1018a(12) =5180a(13) =22581a(14) =41649a(15) =52744a(16) =114564a(17) =147454a(18) =174180