Documentation

FormalConjectures.ErdosProblems.«488»

Erdős Problem 488 #

Reference: erdosproblems.com/488

theorem erdos_488 :
(∀ (A : Finset ) (n m : ), m > nA.max n(Finset.filter (fun (x : ) => x {n : | n 1 aA, ¬a n}) (Finset.Icc 1 m)).card / m < 2 * (Finset.filter (fun (x : ) => x {n : | n 1 aA, ¬a n}) (Finset.Icc 1 n)).card / n) False

Let $A$ be a finite set and $$B = \{n \ge 1 : a \nmid n \text{ for all } a \in A\}.$$ Is it true that, for every $m > n \ge \max(A)$, $$\frac{|B \cap [1, m]|}{m} < 2 \frac{|B \cap [1, n]|}{n}?$$