login
Least m>0 such that 6^n-m and n-m are relatively prime.
0

%I #6 Jul 30 2012 17:45:08

%S 2,1,1,1,1,5,1,3,1,1,2,1,1,1,1,3,1,1,1,1,2,3,1,1,1,3,1,1,1,1,2,1,1,1,

%T 1,5,1,1,1,1,3,1,1,1,1,3,1,1,1,3,2,1,1,1,1,3,1,1,1,1,2,1,1,3,1,5,1,1,

%U 1,1,3,1,1,1,1,3,1,5,1,1,2,1,1,1,1,3,2

%N Least m>0 such that 6^n-m and n-m are relatively prime.

%e gcd(6^8-1,7) = 7, gcd(6^8-2,6) = 2, gcd(6^8-3,5) = 1, so a(8) = 3.

%t Table[m = 1; While[GCD[5^n - m, n - m] != 1, m++]; m, {n, 1, 140}]

%Y Cf. A214716.

%K nonn,easy

%O 1,1

%A _Clark Kimberling_, Jul 27 2012