Numbers k such that (10*7^k -1)/3 is prime.

Terms

a(0) =0a(1) =1a(2) =2a(3) =14a(4) =29a(5) =38a(6) =40a(7) =59a(8) =62a(9) =64a(10) =76a(11) =80a(12) =101a(13) =491a(14) =1024a(15) =1814a(16) =1826a(17) =13733a(18) =50516