olymmath

ISL 2007 N7

    For a prime pp and a positive integer nn, denote by νp(n)\nu_{p}(n) the exponent of pp in the prime factorization of nn !. Given a positive integer dd and a finite set {p1,…,pk}\left\{p_{1}, \ldots, p_{k}\right\} of primes. Show that there are infinitely many positive integers nn such that d∣νpi(n)d \mid \nu_{p_{i}}(n) for all 1≤i≤k1 \leq i \leq k. (India)

    Official text Transcription from NuminaMath olympiads, checked word for word against the official paper. Quoted with source.

    Official text: IMO 2007 Shortlist booklet, page 64.

    Solutions

    Official solution Solution 1 by the IMO Problem Selection Committee

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