OFFSET
1,1
EXAMPLE
gcd(6^8-1,7) = 7, gcd(6^8-2,6) = 2, gcd(6^8-3,5) = 1, so a(8) = 3.
MATHEMATICA
Table[m = 1; While[GCD[5^n - m, n - m] != 1, m++]; m, {n, 1, 140}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jul 27 2012
STATUS
approved