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- Thu Mar 11, 2021 1:24 pm
- Forum: National Math Olympiad (BdMO)
- Topic: BdMO National Higher Secondary 2020 P8
- Replies: 8
- Views: 9257
Re: BdMO National Higher Secondary 2020 P8
Let us try to count the number of kawaii permutations in $1,2,3,4, \cdots (n+1)$ Now let us take a choose any number(When in ascending order). Then we can find a kawaii permutation by exchanging it with any number less than itself. All the other numbers must stay in their same position or else we w...