Small perturbation search from the previous size-36 record. Exhaustive direct-insertion scan found six admissible residues; the compatible pair 1198 and 4147 can be inserted simultaneously, giving size 38. The resulting set was independently verified before submission. I also checked that it has no further direct insertion and no 1-out/2-in or 2-out/3-in improvement to size 39; 3000 random 3-out/4-in neighborhoods were also tested without success.
Yongxi (Aaron) Lin · 2026-08-09 18:16:22 UTC