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Long Intervals Without Distinct Multiples of the First $n$ Positive Integers

Number Theory 2026-07-11 v1 Combinatorics

Abstract

For positive integers nn and mm, let f(n,m)f(n,m) be the least integer h0h\ge0 such that (m,m+h](m,m+h] contains distinct integers a1,,ana_1,\ldots,a_n satisfying iaii\mid a_i for 1in1\le i\le n, and put F(n)=maxmNf(n,m)F(n)=\max_{m\in\mathbb{N}} f(n,m). A recent theorem of van Doorn [INTEGERS, 2026; arXiv:2601.16972] gives F(n)f(n,n)>0.36nlogn/loglognF(n)-f(n,n)>0.36\,n\log n/\log\log n for sufficiently large nn. We prove lim infnF(n)f(n,n)nlogn1e. \liminf_{n\to\infty} \frac{F(n)-f(n,n)}{n\log n} \ge \frac{1}{\mathrm{e}}. Thus, for every fixed c<1/ec<1/\mathrm{e} and all sufficiently large nn, some interval of length cnlognc\,n\log n contains no system of pairwise distinct multiples of 1,2,,n1,2,\ldots,n. The proof applies an Erd\H{o}s--Pomerance smooth-number obstruction at starting points mnlognm\asymp n\log n, using local saddle-point estimates of Hildebrand and Tenenbaum.

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Cite

@article{arxiv.2607.10431,
  title  = {Long Intervals Without Distinct Multiples of the First $n$ Positive Integers},
  author = {Scott Duke Kominers},
  journal= {arXiv preprint arXiv:2607.10431},
  year   = {2026}
}

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19 pages