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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. For every fixed u>1u>1 there are infinitely many nn such that the t(n)=⌊log⁡4n/log⁡(3u)⌋t(n)=\lfloor\log_4n/\log(3u)\rfloor consecutive integers n+1,…,n+t(n)n+1,\dots,n+t(n) are all n1/un^{1/u}-smooth, where log⁡4\log_4 is the four-fold iterated logarithm (Theorem 1, p. 267). Since t(n)→∞t(n)\to\infty, for every ϵ>0\epsilon>0 and k≥2k\ge2 there are infinitely many mm with m+1,…,m+km+1,\dots,m+k all mϵm^\epsilon-smooth. The source card is Balog and Wooley 1998.

Covers. The wording of Problem 369, which is trivially true, since 1,…,k1,\dots,k are nϵn^\epsilon-smooth once n>k1/ϵn>k^{1/\epsilon}, as the site notes; the theorem gives it with a nontrivial run: fix one of the infinitely many mm; for every n≥m+kn\ge m+k the run m+1,…,m+km+1,\dots,m+k lies in {1,…,n}\{1,\dots,n\} and each member is mϵm^\epsilon-smooth, hence nϵn^\epsilon-smooth. The first of the two readings described on the problem page, that each member xx of the run be xϵx^\epsilon-smooth, follows directly, since mϵ≤xϵm^\epsilon\le x^\epsilon. The second, that the run lie in [n/2,n][n/2,n], follows for infinitely many nn (take nn with m+k≤n≤2mm+k\le n\le2m). Not covered: the second reading for all large nn, which needs the further construction of Yang 2026 or the theorem of Bober, Fretwell, Martin and Wooley 2020. The site's curator reports that Wooley described the paper's problem as slightly different, with a stronger uniformity that yields only infinitely many nn.

Acceptance. Published in J. Austral. Math. Soc. Ser. A 64 (1998), no. 2, 266–276, a refereed journal, in the issue dated April 1998 in the publisher's record, which dates this page (refereed). The site's curator, Thomas F. Bloom, records in the problem's commentary (page last edited 2026-04-28) that the first strengthening follows from this result and that the second follows from it for infinitely many nn (reviewed). Eggleton and Selfridge [EgSe76] had earlier given, for every ϵ>0\epsilon>0, infinitely many runs of five consecutive integers n,…,n+4n,\dots,n+4 each nϵn^\epsilon-smooth, which the site notes sits oddly with Erdős and Graham's remark that the problem was open even for k=2k=2; that result is the partial claim Eggleton and Selfridge 1976, and the paper's section 2 comparison (pp. 267–268) records its smoothness bounds and corrects a minor oversight in that result's source.

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