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Problem #312: Does there exist some $c>0$ such that, for any $K>1$,...

Does there exist some $c>0$ such that, for any $K>1$, whenever $A$ is a sufficiently large finite multiset of integers with $\sum_{n\in...

Problem Statement

Does there exist some $c>0$ such that, for any $K>1$, whenever $A$ is a sufficiently large finite multiset of integers with $\sum_{n\in A}\frac{1}{n}>K$ there exists some $S\subseteq A$ such that\[1-e^{-cK} < \sum_{n\in S}\frac{1}{n}\leq 1?\]
Categories: Number Theory Unit Fractions

Progress

Erdős and Graham knew this with $e^{-cK}$ replaced by $c/K^2$.

Source: erdosproblems.com/312 | Last verified: January 14, 2026

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