Question 30
Determine all positive integers $n$ for which there exists a divisor $d$ of $n$ such that
$$
dn + 1 \mid d^2 + n^2.
$$
$$
dn + 1 \mid d^2 + n^2.
$$
MathNet 2015-part-02 — 191 problems (EN–VI) Question 30
Math Olympiad Vault · MathNet 2015-part-02 — 191 problems (EN–VI)