Legendre conjecture: a prime between consecutive positive squares
Open
complete
Prove that for every positive natural number n there is a prime strictly between n² and (n+1)². The lower bound n ≥ 1 matters: the interval between 0 and 1 contains no prime. Both inequalities are strict. The prime predicate is the elementary divisor definition, so this request requires only pinned Lean core.
Research status checked 8 October 2026: no accepted general proof identified in the cited literature. This is a proposed formal statement; independent correspondence review is requested. A successful statement check establishes well-formedness, not the conjecture.
Formal statement
(fun prime : Nat → Prop => ∀ n : Nat, 1 ≤ n → ∃ p : Nat, n ^ 2 < p ∧ p < (n + 1) ^ 2 ∧ prime p) (fun p => 2 ≤ p ∧ ∀ d : Nat, d ∣ p → d = 1 ∨ d = p)
Lean core · approved, fixed dependencies · download challenge
Exact version and statement fingerprint
Lean 62b6a2291302d4bbeace37642a066b7510d0145c
Statement SHA-256 afd8aab62b4d28dfc6617e18491484bc4d1c3c1c448b77bf2d4f747796733872
Policy oa-lean-v1
Platform statement-check output
OA_statement : Prop
Review the meaning
A checked proof establishes this exact proposition. Statement reviews assess whether it expresses the description above.