Open. Two accepted partial claims give refereed upper bounds: Hegyvári's $f(n)\le(2/3+o(1))n$ (Acta Math. Hungar. 48 (1986); claim page (Hegyvári, 1984)) and Coppersmith and Phillips's $f(n)\le(2/3-1/512)n+O(\log n)$ (SIAM J. Discrete Math. 9 (1996); claim page (Coppersmith and Phillips, 1996)). Two partial claims are pending, neither reviewed: a claim of 27 July 2026 by Lenthall-Cleary (using GPT-5.6 Sol, as the proof-claims tab names it), the upper bound $f(n)\le n/2+O(n^{2/3})$ with its finite inequality in Lean 4 (claim page (Lenthall Cleary, 2026)); and Pickhardt's manuscript, written with the Paratelligent Research Agent and linked in the discussion thread on 31 August 2026, the lower bound $f(n)\ge(4/\sqrt3-o(1))\sqrt n$ and an upper bound of the same shape with a smaller second-order constant (claim page (Pickhardt, 2026)). None of the four touches the question $f(n)=o(n)$. The site's label was OPEN on 2026-10-07 (page last edited 12 January 2026).