A201457 - OEIS

%I #5 Mar 30 2012 18:36:00

%S 5,11,1,11,23,29,17,31,13,37,61,11,35,149,17,151,17,17,17,13,59,17,73,

%T 47,43,13,113,77,119,97,125,83,13,421,103,103,77,23,23,79,5,107,7,37,

%U 59,113,11,1,169,887,137,41,113,71,277,413,97,91,227,337,97,353,233,953,5,139,77,473,73,167,275,67,49,97,365,73,223,241,115

%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. A191618, A200921, A201134.

%K nonn

%O 1,1

%A _Michel Lagneau_, Dec 01 2011