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MathNet 2015-part-01 — 191 problems (EN–VI) Question 25

Math Olympiad Vault · MathNet 2015-part-01 — 191 problems (EN–VI)

Question 25

Anton chooses as starting number an integer $n \ge 0$ which is not a square. Berta adds to this number its successor $n + 1$. If this sum is a perfect square, she has won. Otherwise, Anton adds to this sum, the subsequent number $n + 2$. If this sum is a perfect square, he has won. Otherwise, it is again Berta's turn and she adds the subsequent number $n + 3$, and so on.
Prove that Anton wins with infinitely many starting numbers.