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MathNet 2021 — Part 10 Question 5

Math Olympiad Vault · MathNet 2021 — Part 10

Question 5

Suppose $a$, $b$, and $c$ are positive integers such that $a + b + c = 23$ and $\gcd(a, b) + \gcd(b, c) + \gcd(c, a) = 9$. What is the sum of all possible distinct values of $a^2 + b^2 + c^2$?
  1. 259
  2. 438
  3. 516
  4. 625
  5. 687