Wiki
Wiki

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

Updated


Claim. With H(x,z)H(x,z) the least number of integers up to xx divisible by no element of a set S\mathcal S of integers greater than 11 with ∑s∈S1/s≤z\sum_{s\in\mathcal S}1/s\le z (the paper's condition (3)), Theorem 5 states that for every fixed Z>1Z>1, uniformly for 1≤z≤Z1\le z\le Z and x≥2x\ge2,

H(x,z)≍xexp⁡(1−z)log⁡x.H(x,z)\asymp\frac{x^{\exp(1-z)}}{\log x}.

Taking z=Cz=C: for C=1C=1 the count has exact order x/log⁡xx/\log x, which gives the asked lower bound with c=1c=1, and for a fixed C>1C>1 the count is at most a constant times xe1−C/log⁡xx^{e^{1-C}}/\log x, below x/(log⁡x)cx/(\log x)^c for every c>0c>0 and all large xx, so the asked lower bound fails. With the union bound for 0<C<10<C<1, the question is answered yes for 0<C≤10<C\le1 and no for C>1C>1, the same answer, and the same disproof of the bound read for every C>0C>0, as Ruzsa's claim, whose Theorem I the paper names as the result it improves. The first part of Theorem 5, together with Theorem 4 and Corollary 2, gives H(x,1)≤(ae−δ+o(1))x/log⁡xH(x,1)\le(ae^{-\delta}+o(1))x/\log x with ae−δ≈0.878ae^{-\delta}\approx0.878, and Question 2 asks whether this is the asymptotic. The source is A. Weingartner, The Schinzel-Szekeres function, Res. Number Theory 11 (2025), no. 3, Paper No. 63, 32 pp., DOI 10.1007/s40993-025-00643-9 (published 17 June 2025); arXiv:2310.13038, v1 of 19 October 2023, v2 of 13 June 2025. Library home: weingartner_2025_schinzel_szekeres_function.

Formulation. The paper's H(x,z)H(x,z) excludes 11 from the sifting set, as the problem page's corrected Statement does; see the formulation note on Ruzsa's claim page.

Acceptance. Refereed: the paper appeared in Research in Number Theory. Reviewed: the site's curator, Thomas Bloom, who is independent of the author, credits the paper in the curator's commentary (page last edited 8 April 2026, accessed 2026-09-05 and 2026-10-07) with the exact order HC(x)≍xe1−C/log⁡xH_C(x)\asymp x^{e^{1-C}}/\log x for fixed C>1C>1 and with the finer estimates at C=1C=1, and a thread comment of 18 December 2025 derives the negative answer for C>1C>1 from Theorem 5.

Depends on. No page of this wiki.