%I #7 Mar 30 2012 17:34:14
%S 2801,16148168401,
%T 85053461164796801949539541639542805770666392330682673302530819774105141531698707146930307290253537320447270457
%N Primes of the form (7^k-1)/6.
%C The next term, for k=149, has 126 digits.
%t Select[(7^Range[200]-1)/6, PrimeQ]
%Y Cf. A023000 ((7^n-1)/6), A004063 (n such that (7^n-1)/6 is prime).
%K nonn,bref
%O 1,1
%A _Roger L. Bagula_, Mar 15 2005