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Erdős problem 346

Let A={1a1<a2<}A=\{1\leq a_1< a_2<\cdots\} be a set of integers such that A\BA\backslash B is complete for any finite subset BB and not complete for any infinite subset BB. If an+1/an1+ϵa_{n+1}/a_n \geq 1+\epsilon for all nn, must limnan+1/an=(1+5)/2\lim_n a_{n+1}/a_n=(1+\sqrt{5})/2? Under the reading where the ratio limit is assumed to exist, a Lean-verified argument forces the limit to be the golden ratio; a separate construction disproves the literal statement where convergence is not assumed.

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  • AI collaborating with humans

    Erdős AI contributions wiki · 21 Jun, 2026

    Machine
    Codex, GPT
    People
    Kenta Kitamura
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  • AI alongside literature

    Erdős AI contributions wiki · 19 Jun, 2026

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    Codex, GPT-5.5 Pro
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  • argument

    VibeMathed

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    ChatGPT, Codex
    People
    Kenta Kitamura
    Reported outcome
    candidate
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