OFFSET
1,4
COMMENTS
Conjecture: a(n) = 3 if and only if n = 330*k-209 for some k>=1.
LINKS
Clark Kimberling, Table of n, a(n) for n = 1..1000
EXAMPLE
gcd(64-1,729-1) = 7 and gcd(64-2,729-2) = 1, so a(6) = 2.
MATHEMATICA
Table[m = 1; While[GCD[2^n - m, 3^n - m] != 1, m++]; m, {n, 1, 140}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jul 27 2012
STATUS
approved