Erdős Problem a Daythe open tracker

Erdős Problem #50

OPENdatabase updated 2025-08-31

No proof or disproof is known, and it isn't known whether a finite computation could settle it.

What the community database records, not our verdict. erdosproblems.com no longer shows statuses (why).

A function \(f : \mathbb{R} \to \mathbb{R}\) is the asymptotic distribution function of the values of \(\varphi(n)/n\) if for all \(c \in [0, 1]\), the natural density of \(\{n : \varphi(n) < cn\}\) exists and equals \(f(c)\).

A function \(f : \mathbb{R} \to \mathbb{R}\) is purely singular (or singular continuous) on a set \(s \subseteq \mathbb{R}\) if it is continuous on \(s\) and its derivative within \(s\) equals zero almost everywhere on \(s\) with respect to Lebesgue measure.

Schoenberg [Sch38] proved that the asymptotic distribution function of \(\varphi(n)/n\) exists. That is, for any \(c \in [0, 1]\), the proportion of integers \(n \le N\) satisfying \(\varphi(n)/n < c\) approaches a limit as \(N \to \infty\). This limit function is the cumulative distribution function of the values of \(\varphi(n)/n\).
Statement as formalized in Formal Conjectures (Google DeepMind, Apache-2.0) · their label: research solved · 2 further variants / known partial results in the Lean file. The authoritative wording is on erdosproblems.com/50.
Prize$250
Topicsnumber theory
Statement in LeanFormal Conjectures
Solution in Leanno
Original pageerdosproblems.com/50
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Proved, modulo Schoenberg/Mertens/Bertrand, a dense continuum-sized family of irrational points generated by an explicit recursion with infinite upper-right Dini derivative; the possibility of a finit

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