Erdős problem 692 · problems.science

Let $\delta_1(n,m)$ be the density of the set of integers with exactly one divisor in $(n,m)$ . Is $\delta_1(n,m)$ unimodular for $m>n+1$ (i.e. increases until some $m$ then decreases thereafter)?

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FormalConjectures/ErdosProblems/

692.lean

Retained formal statement1 of 5

Let $\delta_1(n,m)$ be the density of the set of integers with exactly one divisor in $(n,m)$ . Is $\delta_1(n,m)$ unimodular for $m>n+1$ (i.e. increases until some $m$ then decreases thereafter)?

Cambie has calculated that unimodularity fails even for $n=2$ and $n=3$ .

FormalConjectures/ErdosProblems/692.leanErdos692.erdos_692.parts.i1 lineExact file

1False ↔ ∀ (δ : ℕ → ℕ → ℝ), (∀ (a b : ℕ), Erdos692.IsDelta₁ a b (δ a b)) → ∀ (n : ℕ), UnimodularOn (δ n) (n + 1)

SolvedStatement only, no proof

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