Erdős Problem 9
Is the upper density of the set of odd numbers that cannot be expressed as a prime plus two powers of 2 positive?
Mathematical statement
Is the upper density of the set of odd numbers that cannot be expressed as a prime plus two powers of 2 positive?
Statement source: Erdős Problems statement material
Statement terms: Source-specific
Source-specific terms. Therefore does not assert reuse rights beyond attributed display.
Statement artifacts, not proofs
These records expose exact Lean propositions and statement-only wrappers. Defining a proposition does not supply a proof of it. A placeholder-bearing target also contains no proof. Elaboration checks syntax and types; it does not certify that a formalization perfectly captures every nuance of the informal problem.
Pinned Lean formulation 1
erdos_9
theorem erdos_9 : answer(sorry) ↔ 0 < Erdos9A.upperDensity := by sorry- Statement source
- Formal Conjectures
- Lean version
- v4.27.0
- Placeholder
- Present; no proof artifact
- Source evidence
- Pinned source index
- Fidelity review
- Community formulation
References