Question 135
Let $n \ge 2$ be a positive integer. Two opposite corner squares are removed from an $n \times n$ board. In how many ways can $n$ chess pieces be placed on this board so that no two pieces are in the same row or column? (Matko Ljulj)
Math Olympiad Vault · MathNet 2019-part-02 — 184 problems (EN–VI)