Formal target: Corpus.Erdos1072.erdos_1072.variants.littleo
Erdős, Hardy, and Subbarao [HaSu02], believed that the number of $p \le x$ for which $f(p)=p−1$ is $o(x/\log x)$.
Exact formal statement
Asymptotics.IsLittleO.{0, 0, 0} Filter.atTop.{0}
(fun x =>
Nat.cast.{0}
(Set.ncard.{0}
(Inter.inter.{0}
(Set.ofPred.{0} fun p => And (Nat.Prime p) (Eq.{1} (Corpus.Erdos1072.f p) (HSub.hSub.{0, 0, 0} p 1)))
(Set.Icc.{0} 0 x))))
fun x => HDiv.hDiv.{0, 0, 0} (Nat.cast.{0} x) (Real.log (Nat.cast.{0} x))This target is a formal statement, not a proof of the problem.
Environment availability: available.