Permutations That Stay Ahead

Problem

Find the number of permutations of $1, 2, 3, 4, 5, 6$ such that for each $k = 1, 2, 3, 4, 5$ , at least one of the first $k$ terms of the permutation is greater than $k$ .

Answer

Solution

Difficulty	5/10
Topics	combinatorics, Counting, Recursion

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