Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.
Updated
Claim. The answer to Problem 379 is yes: , where is the largest such that every with is divisible by for some prime depending on . The proof emerged in the problem's discussion thread on the site between 27 and 28 August 2025, from an exchange among Stijn Cambie, Vjekoslav Kovač and Terence Tao, with Tao's comment of 28 August 2025 giving the complete argument. It is a construction: let and let be a prime with ; then has . For such every with is divisible by or by . The prime is handled through the identity : since , either or . The prime is handled through Euler's theorem, , and the identity , which transfers the factor of to when divides neither nor , hence not ; the remaining cases are excluded by the size condition . Taking with a prime for each gives the unbounded sequence. The site also records a simpler construction, , from an Art of Problem Solving discussion; it is not credited to a named author and has no page here.
Formalization. Tao's Lean development, linked above at a pinned commit
of Tao's analysis repository, states in its header that it formalizes a proof
of the problem arising from the conversations among the three and points to
the thread; its final theorem is the limsup statement with defined as
the supremum above. The file was first committed on 28 August 2025. The
formal-conjectures statement file for the problem names two formal proofs:
Tao's file and a proof of erdos_379 at a commit of a contributor's fork
that GitHub no longer serves. That proof was the first commit of a pull
request to formal-conjectures, whose second commit removed the proof body
and kept only the link before the merge of 13 April 2026, so the merged
statement stays unproved; the proof is linked above at that first commit;
its description says that it follows the argument of Cambie, Kovač and Tao,
its helper lemmas are headed as coming from Tao's proof, and its author
records assistance from Claude (Anthropic) for the Lean translation. This
corpus has not built or audited either development, so neither is listed as
evidence.
Depends on. No page of this wiki.
Acceptance. Thomas Bloom, the site's curator, marks the problem proved, credits Cambie, Kovač and Tao on the problem page (last edited 12 January 2026) and records the Lean formalization in the site's label; the community database lists the problem's status as proved (Lean) as of its last update, dated 31 August 2025. There is no refereed write-up and the result exists only as the thread posts and the Lean file; the acceptance rests on the curator's documented review.