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MathNet 2003 — Part 02 Question 48

Math Olympiad Vault · MathNet 2003 — Part 02

Question 48

A permutation $\sigma:\{1,2, \ldots, n\} \rightarrow\{1,2, \ldots, n\}$ is called straight if and only if for each integer $k, 1 \leq k \leq n-1$ the following inequality is fulfilled
$$
|\sigma(k)-\sigma(k+1)| \leq 2
$$
Find the smallest positive integer $n$ for which there exist at least 2003 straight permutations.