The board / number theory / #635
Erdős Problem #635
OPENdatabase updated 2026-01-30
No proof or disproof is known, and it isn't known whether a finite computation could settle it.
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exact M_2(N)=ceil(N/2)+ceil(floor(log_2 N)/2) is certified for every N<=256, M_t(N) is proved exactly when 3t>N, and a precise Hall-expansion lemma isolates the unproved uniform t=2 step.
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