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Determine n

Posted: Sun May 21, 2017 2:44 am
by Katy729
Determine if there are integers $n$ so that $n^2-4$ has exactly $10$ divisors (positive).

Re: Determine n

Posted: Fri Jun 02, 2017 8:49 am
by asif e elahi
Sketch:
Suppose $n$ is such an integer. Prove that $n^2-4=pq^4$ for some prime $p,q$. Deduce that $q=2$.......