The OEIS is supported by the many generous donors to the OEIS Foundation.
%I #5 Mar 30 2012 18:36:00
%S 1,1,5,7,7,11,5,29,13,29,5,1,77,1,13,101,65,77,175,29,77,121,49,23,41,
%T 31,613,101,13,37,127,47,197,31,107,97,275,17,619,47,7,199,85,31,47,
%U 17,97,253,17,37,5,103,215,119,335,257,277,121,313,89,157,187,25,7,571,11,197,53,13,101,49,199,67,389,109,13,25,41,337,647,77
%N Least k such that (7^n - k)*7^n - 1 is a prime number.
%t Table[k = 0; While[!PrimeQ[(7^n - k)*7^n - 1], k++]; k, {n, 85}]
%Y Cf. A191620, A200922, A201132.
%K nonn
%O 1,3
%A _Michel Lagneau_, Dec 01 2011