Erdős problem 987
Clunie [Cl67] proved that there exists an infinite sequence on the unit circle with for all . Translating , the natural domain of is the half-open unit interval , matching the original [Er64b]/[Cl67] statement (any unit complex number is allowed, including , i.e. ).
Sources
FormalConjectures/ErdosProblems/
987.lean
Retained formal statement
Clunie [Cl67] proved that, for every infinite sequence , for infinitely many . (Tao independently found a proof.)
∀ (x : ℕ → ℝ), (∀ (j : ℕ), x j ∈ Set.Ioo 0 1) → ∃ c > 0, ∃ᶠ (k : ℕ) in Filter.atTop, ↑(c * √↑k) ≤ Erdos987.A x k