RMO 2024 Problem 1 | Nice Permutations | Combinatorics for Math Olympiad

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  • Опубліковано 6 лис 2024

КОМЕНТАРІ • 4

  • @NORAD-f2y
    @NORAD-f2y День тому

    really easy way to prove the first part
    take k = n , sum of the numbers will be n(n+1)/2 which is divisible by n when it is odd.
    thus there is no nice rearrangement

  • @sagnikbiswas3268
    @sagnikbiswas3268 День тому

    Really light problem

  • @RaghavMukhija
    @RaghavMukhija 2 дні тому +1

    k(2k + 1) / 2k
    Cancel the common k term, which leaves:
    (2k + 1) / 2
    Since 2k + 1 is odd and 2 is even, dividing an odd number by an even number does not yield an integer. Therefore, k(2k + 1) is never divisible by 2k.

  • @BigFatSandwitch
    @BigFatSandwitch 4 дні тому +1

    k(2k+1) is never divisible by 2k because 2 doesn't divide 2k+1