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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. There is an absolute constant C>0C>0 such that infinitely many positive integers nn satisfy ω(n+k)≤Ω(n+k)≤Clog⁡k\omega(n+k)\le\Omega(n+k)\le C\log k for every integer k≥2k\ge2. This is Theorem 1.1 of Cheuk Fung (Joshua) Lau, On the number of prime factors of consecutive integers, arXiv:2604.15042 (v1 2026-04-16, v2 2026-06-24), stated for Ω\Omega, the number of prime factors counted with multiplicity, and hence for ω≤Ω\omega\le\Omega. It answers the question of Problem 248 yes after a shift of nn: for such an nn put n′=n+1n'=n+1; then for every j≥1j\ge1,

ω(n′+j)=ω(n+(j+1))≤Clog⁡(j+1)≤Cj,\omega(n'+j)=\omega(n+(j+1))\le C\log(j+1)\le Cj,

since log⁡(j+1)≤j\log(j+1)\le j for j≥1j\ge1, so infinitely many n′n' have ω(n′+j)≪j\omega(n'+j)\ll j for all j≥1j\ge1 with an absolute implied constant. The paper's random models (Conjectures 5 and 6) say that the bound Clog⁡kC\log k is sharp up to the constant. The proof refines the probabilistic sieve argument of Tao and Teräväinen: nn is drawn from [x,2x][x,2x] weighted by a product of Selberg sieve weights with polynomially decaying levels Rk=xc/k50R_k=x^{c/k^{50}}, and a sieve-weighted concentration estimate for Ω(n+k)\Omega(n+k) (Proposition 5.5) makes the union bound over k≥2k\ge2 converge. Theorem 1.3 gives the same bound for n−kn-k. The source card is Lau 2026.

Depends on. Nothing in this wiki; the argument is self-contained in the preprint. It refines the method of Tao and Teräväinen 2025 but does not rest on that result.

Acceptance. Reviewed: the site's curator, Thomas F. Bloom, labels the problem PROVED (LEAN) and credits Lau [La26] in the problem's commentary with improving the bound to ω(n+k)≪log⁡k\omega(n+k)\ll\log k for all k≥2k\ge2, noting that ω\omega may be replaced by Ω\Omega (page last edited 2026-04-17, after a thread comment of the same day cited the preprint, which the site marks as addressed); that documented acceptance is the reviewed evidence. Not refereed: the preprint has no journal publication on record. Not formalized: no Lean development of this result is known; the lean-proofs file linked from the Tao–Teräväinen page formalizes their linear bound, not this one.