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Erdős problem 355

Is there a lacunary sequence ANA\subseteq \mathbb{N} (so that A={a1<}A=\{a_1 < \cdots\} and there exists some λ>1\lambda > 1 such that an+1/anλa_{n+1}/a_n\geq \lambda for all n1n\geq 1) such that {aA1a:AA finite}\left\{ \sum_{a\in A'}\frac{1}{a} : A'\subseteq A\textrm{ finite}\right\} contain all rationals in some open interval?

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  • Formalization

    Erdős AI contributions wiki · 30 Jan-13 Mar, 2026

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    Aristotle, Gemini 3
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