Problem

Source: 2020 Dürer Math Competition Finals Day2 E+6 https://artofproblemsolving.com/community/c1622639_2020_

Tags: number theory, divides



Positive integers $a, b$ and $c$ are all less than $2020$. We know that $a$ divides $b + c$, $b$ divides $a + c$ and $c$ divides $a + b$. How many such ordered triples $(a, b, c)$ are there? Note: In an ordered triple, the order of the numbers matters, so the ordered triple $(0, 1, 2)$ is not the same as the ordered triple $(2, 0, 1)$.