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Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.

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Claims

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1969_05_01_ecklund: Ecklund's refereed theorem gives every binomial coefficient in the problem's range a prime divisor at most n/2, apart from 7 choose 3, which proves the corrected statement.

2026_08_17_alexeev: Answers the site's wording (a prime divisor p < n/2), not the corrected Statement (p at most n/2), so it does not count toward the problem's standing. A Lean file in Boris Alexeev's repository refutes the strict bound at 4 choose 2 equal to 6.