Erdős problem 950
This function was considered by de Bruijn, Erdős, and Turán, who showed that . They gave no proofs, but a proof of the (harder) second claim is given by Gorodetsky here [mathoverflow/508491].
Sources
FormalConjectures/ErdosProblems/
950.lean
Retained formal statement
The study of is even harder, and Erdős could not prove that .
True ↔ Asymptotics.IsEquivalent Filter.atTop (fun x => ∑ p ∈ Finset.range x with Prime p, Erdos950.f p ^ 2) fun x => ↑x.primeCountingOpenStatement only, no proof