Erdős problem 198
The answer is no; Erdős and Graham report this was proved by Baumgartner, presumably referring to the paper [Ba75], which does not state this exactly, but the following simple construction is implicit in [Ba75].
Sources
FormalConjectures/ErdosProblems/
198.lean
Retained formal statement
In fact one such sequence is .
This was found and proved by AlphaProof.
It also found .
∃ A, A = {x | ∃ n, n.factorial + n = x} ∧ IsSidon A ∧ ∀ (Y : Set ℕ), Y.IsAPOfLength ⊤ → (A ∩ Y).Nonempty