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MathNet 2010 — Part 07 Question 78

Math Olympiad Vault · MathNet 2010 — Part 07

Question 78

Given a permutation $\pi$ of the set $\{1,2, \ldots, 10\}$, define a rotated cycle as a set of three integers $i, j, k$ such that $i\lt j\lt k$ and $\pi(j)\lt \pi(k)\lt \pi(i)$. What is the total number of rotated cycles over all permutations $\pi$ of the set $\{1,2, \ldots, 10\}$?