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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. Theorem 2.1 of the paper: let f(t)=∏j=1l(ajtkj−bj)f(t)=\prod_{j=1}^{l}(a_jt^{k_j}-b_j) with integers aj≠0a_j\neq0, bjb_j and kj≥1k_j\geq1. Then there is c>0c>0, depending on the kjk_j, such that polynomials g∈Z[t]g\in\mathbb{Z}[t] of arbitrarily large degree dd exist for which f(g(t))f(g(t)) factors as a product of polynomials of degree at most cd/(log⁡log⁡d)1/lcd/(\log\log d)^{1/l}. Applied to f(t)=t(t+1)⋯(t+k−1)f(t)=t(t+1)\cdots(t+k-1), a product of kk linear factors, the theorem gives, for every ϵ>0\epsilon>0 and k≥2k\geq2, a constant θ<1\theta<1 such that for all large nn some kk consecutive integers in [n−nθ,n][n-n^{\theta},n] are all nϵn^\epsilon-smooth: for an integer tt the kk consecutive integers g(t),…,g(t)+k−1g(t),\dots,g(t)+k-1 have every prime factor bounded by a polynomial value of degree at most cd/(log⁡log⁡d)1/kcd/(\log\log d)^{1/k} in tt, hence by nϵn^{\epsilon} once dd is large, and consecutive values of gg are O(n1−1/d)O(n^{1-1/d}) apart, so every large nn has such a run in [n−O(n1−1/d),n][n-O(n^{1-1/d}),n], inside [n−nθ,n][n-n^{\theta},n] for any θ∈(1−1/d,1)\theta\in(1-1/d,1). This deduction was pointed out by Wooley to the site's curator, Thomas F. Bloom, who wrote it out on the forum on 2026-03-27 and records its conclusion in the problem's commentary. The run lies in [n/2,n][n/2,n], so the result settles the question of Problem 369 as written, the formal-conjectures statement erdos_369, and both strengthenings the site proposes: the second directly, and the first because a run of nϵ/2n^{\epsilon/2}-smooth integers above n/2n/2 is mϵm^{\epsilon}-smooth for each of its members mm. It is stronger than the result of Yang 2026, whose run lies in (3n/4,n)(3n/4,n), and than that of Balog and Wooley 1998, which gives infinitely many nn. The source card is Bober, Fretwell, Martin and Wooley 2020.

Acceptance. Published in J. Aust. Math. Soc. 108 (2020), no. 2, 245–261, a refereed journal, online 2019-02-01 in the publisher's record (refereed); the arXiv posting of 2017-10-05 dates this page. The site's curator labels the problem PROVED (LEAN) and credits the paper's main result, in the problem's commentary (page last edited 2026-04-28), with the stronger statement above (reviewed). The Lean proofs linked by formal-conjectures formalize Yang's construction, not this theorem, so formalized is not listed.

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