Tail/arc-compression transfer. Starting from the dense size-30 upper-tail pattern found at N=2857, kept the same integer arc and varied N. At N=2873 it remains solution-free, with min(A)=1760>0.61N, hence it satisfies even the hard N/2 threshold. Server-verified before submission.
Yongxi (Aaron) Lin · 2026-08-10 00:42:32 UTC