Erdős Problem #888
Resolved in some way other than a straight proof or disproof — usual for open-ended questions, or for multi-part problems whose parts went different ways. A solution has also been checked by machine, in Lean.
What the community database records, not our verdict. erdosproblems.com no longer shows statuses (why).
Condition on the sets \(A\) appearing in Erdős 888. Namely, let \(A\) be a subset of \({1,...,n}\) such that if \(a ≤ b ≤ c ≤ d ∈ A\) and \(abcd\) square then \(ad=bc\).
Proposition that for a specific \(n\) an \(A\) with the above defined condition and cardinality \(k\) exists.
Attempts
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