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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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Claim. On printed p. 273 of his 1976 paper, after conjecture (7), Erdős writes: "The best that I can show is nk>k2exp⁡((log⁡k)c)n_k>k^2\exp((\log k)^c) for a certain c>0c>0." Here nkn_k is the least nn such that each of n+1,…,n+kn+1,\ldots,n+k has a prime factor greater than kk, and k(n)=max⁡{k:nk≤n}k(n)=\max\{k:n_k\le n\}, so the bound gives k(n)≤n1/2exp⁡(−(log⁡n)c′)k(n)\le n^{1/2}\exp(-(\log n)^{c'}) for some c′>0c'>0, using log⁡k(n)≥(log⁡n)1/2−o(1)\log k(n)\ge(\log n)^{1/2-o(1)} from display (6). The passage is paged at inequality (6) of the library's source card. The same sentence says he cannot show nk>k2+ϵn_k>k^{2+\epsilon}, which would give k(n)≤n1/2−ck(n)\le n^{1/2-c}.

Covers. The upper bound on k(n)k(n) only; neither question of Problem 962 is settled by it.

Depends on. Erdős 1976, for the lower bound used in the translation to k(n)k(n).

Standing. Claimed. The paper asserts the bound without proof or reference, and no proof of it has been found in print; the curator's thread post of 3 April 2026 reports it as a claimed proof. The proved upper bound is k(n)≤(1+o(1))n1/2k(n)\le(1+o(1))n^{1/2}, from Tao's thread argument, recorded on the problem page.