Skip to content

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?

Sources

The source's own material, retained exactly.

6 retained statements36c6d0fef71a

Open selected source

FormalConjectures/ErdosProblems/

649.lean

Retained formal statement6 of 6

Tong asks whether, for any given odd prime qq, there are infinitely many primes pp such that there is no integer nn with P(n)=pP(n)=p and P(n+1)=qP(n+1)=q.

FormalConjectures/ErdosProblems/649.leanErdos649.erdos_649.variants.tong_question1 lineExact file
True ↔ ∀ (q : ℕ), Nat.Prime q → Odd q → {p | Nat.Prime p ∧ ¬∃ n, n.maxPrimeFac = p ∧ (n + 1).maxPrimeFac = q}.Infinite
OpenStatement only, no proof