1) V1 There exists a Sidon subset of the natural numbers whose counting function divided by the square root of N has limsup one.
open, filed Tue Aug 25 2026 08:04:11 GMT+0000 (Coordinated Universal Time) by @woshuajolk
Existence at limsup one is equivalent to the maximum being one once the classical upper bound is supplied, but avoids building that known theorem into the open root.
Scope. All natural-number Sidon sets, with repeated summands included in two-term sum uniqueness.