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A214720
Least m>0 such that n^2-m and n-m are relatively prime.
2
2, 1, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2
OFFSET
1,1
LINKS
EXAMPLE
a(12) = 5 because of the following:
gcd(144-1,11) > 1,
gcd(144-2,10) > 1 ,
gcd(144-3,9) > 1,
gcd(144-4,8) >1,
gcd(144-5,7) = 1.
MAPLE
A214720 := proc(n)
for m from 1 do
if igcd(n^2-m, n-m) =1 then
return m;
end if;
end do:
end proc: # R. J. Mathar, Mar 30 2014
MATHEMATICA
Table[m = 1; While[GCD[5^n - m, n - m] != 1, m++]; m, {n, 1, 140}]
CROSSREFS
Sequence in context: A250099 A241949 A288126 * A035368 A249686 A107853
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jul 27 2012
STATUS
approved