BdMO National Junior 2019/4
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- Posts:1007
- Joined:Sat Dec 09, 2017 1:32 pm
Find all positive integer $n$ such that $2019+n!$ is a perfect square.
Re: BdMO National Junior 2019/4
n<4 there is no solution.
n>3
$2019+n!\congruent 3(mod 4)$
contradiction!
n>3
$2019+n!\congruent 3(mod 4)$
contradiction!