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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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The claim: infinitely many nn have no representation n=2k+mn=2^k+m with Ω(m)<log⁡log⁡m\Omega(m)<\log\log m, so the first question of Problem 205 has a negative answer; the negative answer to the first is one to the second, whose bound ϵlog⁡log⁡m\epsilon\log\log m is no larger when ϵ≤1\epsilon\le1. It is one to the third because of how the counterexamples are built. For E≥10E\ge10, nn is a multiple of 2E2^E and of 33, with n≡2kn\equiv2^k modulo a product of EE distinct primes at least 55 for each k<Ek<E. So every m=n−2km=n-2^k is positive and divisible by 2E2^E or by those EE primes, hence at least 2E2^E. For any ff with f(m)=o(log⁡log⁡m)f(m)=o(\log\log m), once EE is large, f(m)<log⁡log⁡m≤Ω(m)f(m)<\log\log m\le\Omega(m) for all these mm. The site's commentary (last edited 2026-04-05) credits the disproof to Barreto and Leeham, working with ChatGPT and Aristotle, and its thanks line names Kevin Barreto and Leeham among the contributors; Leeham is the forum account of Liam Price, whose posts display under that name, and who posted the formalization and the write-up. The community database dates the problem's change to disproved on 2026-01-10. In the site's discussion thread on 2026-01-11, Price posted the Aristotle formalization of the construction as a live Lean session (the formalization link above), then a write-up on Overleaf (the preprint link above), which Price describes as ChatGPT's output, and named Kevin Barreto as the collaborator with whom Price had worked on the site's problems 728 and 729 by the same method: asking ChatGPT 5.2 to research the problem and brainstorm, then an offline run of GPT-5.2 Thinking (the same day Price wrote that the model was GPT-5.2 Thinking rather than GPT-5.2 Pro and asked for the note on the community database's GitHub page to be changed) that was not told the problem was open, with Aristotle formalizing the result. The community database's AI-contributions wiki lists the result under Aristotle and GPT-5.2 Thinking as a full solution in Lean. The headers of the later community Lean files say that Wouter van Doorn suggested the approach, ChatGPT made it into a complete informal proof and Aristotle formalized it. The quantified strengthening posted the same day by Tao and Alexeev has its own page, Tao–Alexeev 2026, and is the form the later community Lean files prove; the session linked above proves the log⁡log⁡\log\log form itself, from Mathlib alone.

Depends on. Nothing in this wiki.

Acceptance. Reviewed: the site's curator, Thomas F. Bloom, labels the problem DISPROVED (LEAN) and credits the negative answer to Barreto and Leeham in the problem's commentary (last edited 2026-04-05), and Terence Tao, in the thread on 2026-01-11, described the construction, found it surprisingly simple and listed it as a full solution under Section 1, primary contributions, of the AI-contributions wiki of the community database Tao maintains. The same day Nat Sothanaphan posted a human-readable version of the quantified Lean proof and wrote that they had checked everything by hand; that write-up is linked from the Tao–Alexeev page. No refereed publication exists: the Overleaf write-up is ChatGPT's output and unrefereed, and no library card digests it. The Lean session linked above is a community file that this corpus has not built or audited, so no formalized evidence is listed and the evidence is reviewed alone. The Lean suffix of the site's label is a catalog label; what the linked formal files prove is recorded on the problem page and on the Tao–Alexeev page.