Question 20
Find all ordered triples of primes $(p, q, r)$ such that
$$
p \mid q^r + 1, \quad q \mid r^p + 1, \quad r \mid p^q + 1.
$$
$$
p \mid q^r + 1, \quad q \mid r^p + 1, \quad r \mid p^q + 1.
$$
MathNet 2003 — Part 03 Question 20
Math Olympiad Vault · MathNet 2003 — Part 03