Suppose there is a set of {1,2,...,n} and we have to find the number of permutations of this set such that there is no increasing sub array of length 3. For example, if n=4, then 1,4,2,3 is not a permissible permutation as 1,2,3 is an increasing sub sequence. I know the answer is Catalan number but I am not being able to find any bijection with the common examples
2026-03-25 23:10:04.1774480204
Counting number of permutations of {1,2,...,n} such that there is no 123 sub sequence.
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