Erdős Problem #654
OPENdatabase updated 2025-08-31
No proof or disproof is known, and it isn't known whether a finite computation could settle it.
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Proved \(f(2)=1,\ f(3)=1,\ f(4)=2,\ f(5)=f(6)=3\), established \(3\leq f(7)\leq4\) and \(4\leq f(8)\leq5\), and supplied exact no-four-concyclic constructions and checks; the asymptotic \((1/3+c)n\) q
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