The board / irrationality / #259
Erdős Problem #259
PROVED LEANdatabase updated 2026-04-21
The statement as posed is true, and a proof exists. A solution has also been checked by machine, in Lean.
What the community database records, not our verdict. erdosproblems.com no longer shows statuses (why).
Is \(\sum_{n} \mu(n)^2\frac{n}{2^n}\) irrational? This is true, and was proved by Chen and Ruzsa. [ChRu99] Chen, Yong-Gao and Ruzsa, Imre Z., On the irrationality of certain series. Period. Math. Hungar. (1999), 31--37.
Statement as formalized in Formal Conjectures (Google DeepMind, Apache-2.0) · their label: research solved. The authoritative wording is on erdosproblems.com/259.Prizenone
Topicsirrationality
Statement in LeanFormal Conjectures
Solution in Leanyes
OEISA371134
Original pageerdosproblems.com/259
Attempts
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