Erdős problem 1209
Let be a sequence of integers which tends to infinity sufficiently fast. If there is an such that all are primes then must there exist infinitely many such ?
Sources
FormalConjectures/ErdosProblems/
1209.lean
Let be a sequence of integers which tends to infinity sufficiently fast. If there is an such that all are primes then must there exist infinitely many such ?
Erdős [Er80] wrote 'unless I overlook a trivial way of getting a counterexample these questions are quite hopeless'. There is indeed a trivial counterexample (a variant of the construction in [erdosproblems.com/429]): define and for let be a prime such that , where is some prime not dividing . This sequence can be made to grow arbitrarily fast
See also [erdosproblems.com/429] and [erdosproblems.com/1102].
False ↔ ∃ f, ∀ (a : ℕ → ℕ), StrictMono a → (∀ (k : ℕ), f k ≤ a k) → (∃ n, ∀ (k : ℕ), Nat.Prime (n + a k)) → {n | ∀ (k : ℕ), Nat.Prime (n + a k)}.Infinite