Caveats on novelty: Steinerberger's r=9 list carries an ellipsis and he writes 'Many more such solutions exist', and the original Selfridge–Weintraub r=9 solution values are not listed in any accessible source (ErGr80 p.81 gives none; Steinerberger reports only 'all n found were even'), so the (9,9), (20,6561), (25,729) and (14,729) novelty claims are relative to the explicitly recorded examples; Stijn Cambie is active on this problem (page edited 2025-10-28) and may hold unpublished sweeps covering the (4,3) orbits.