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MathNet 2008-part-02 — 165 problems (EN–VI) Question 132

Math Olympiad Vault · MathNet 2008-part-02 — 165 problems (EN–VI)

Question 132

Consider a chessboard $n \times n$ where $n \gt 1$ is a positive integer. We select the centers of $2 n-2$ squares. How many selections are there such that no two selected centers lie on a line parallel to one of the diagonals of the chessboard?