Question 173
Determine all natural numbers $a$ for which there exist prime numbers $p$, $q$, $r$, not necessarily distinct, such that
$$
a = \frac{p+q}{r} + \frac{q+r}{p} + \frac{r+p}{q}
$$
$$
a = \frac{p+q}{r} + \frac{q+r}{p} + \frac{r+p}{q}
$$
MathNet 2015-part-02 — 191 problems (EN–VI) Question 173
Math Olympiad Vault · MathNet 2015-part-02 — 191 problems (EN–VI)