Primes of the form m = 7^i + 7^j - 1, where i > j >= 0.

Terms

a(0) =7a(1) =349a(2) =19207a(3) =117991a(4) =120049a(5) =823591a(6) =5765143a(7) =5882449a(8) =6588343a(9) =40353949a(10) =282475591a(11) =2017680349a(12) =2259801991a(13) =13841289601a(14) =14123762449a(15) =96894775207a(16) =96929364013a(17) =678223072897a(18) =678223075249