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A214708
Least m>0 such that 4^n-m and 5^n-m are relatively prime.
2
1, 2, 1, 2, 2, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 1, 2, 2, 2, 2, 2, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 2, 2, 2, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 2
OFFSET
1,2
COMMENTS
a(248) = 3. Is every term < 4?
LINKS
EXAMPLE
gcd(256-1,625-1) = 3 and gcd(256-2, 625-2) = 1, so a(4) = 2.
MATHEMATICA
Table[m = 1; While[GCD[4^n - m, 5^n - m] != 1, m++]; m, {n, 1, 140}]
CROSSREFS
Sequence in context: A070304 A275308 A233138 * A083952 A245225 A214860
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jul 27 2012
STATUS
approved