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Erdős problem 649

Let P(m)P(m) denote the greatest prime factor of mm. Is it true that, for any two primes p,qp,q, there exists some integer nn such that P(n)=pP(n)=p and P(n+1)=qP(n+1)=q?

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6 retained statements36c6d0fef71a

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FormalConjectures/ErdosProblems/

649.lean

Retained formal statement3 of 6

Problem 6 in the 12th Romanian Master of Mathematics Competitions in 2020 was to prove that there exist infinitely many odd primes pp such that, for every nn, P(n)P(n+1)≠2pP(n)P(n+1)\neq 2p.

FormalConjectures/ErdosProblems/649.leanErdos649.erdos_649.variants.rmm_20201 lineExact file
{p | Nat.Prime p ∧ Odd p ∧ ∀ (n : ℕ), n.maxPrimeFac * (n + 1).maxPrimeFac ≠ 2 * p}.Infinite
TextbookStatement only, no proof