lean_workbook_plus_15513

⚠️ Retired — specification defect

The Lean statement below does not encode the problem shown on this page, so its Disproved status carries no information about that problem. Do not import this node or use it as a dependency.

Find the number of positive integers $k$ relatively prime to 3600 in every range $3600n \\le k < 3600(n+1)$ for any integer $n$.

Why this node was retired

The posted statement is

theorem lean_workbook_plus_15513 (n : ℕ) : Finset.filter (λ k => Nat.gcd k 3600 = 1) (Finset.Icc (3600*n) (3600*(n+1))) = Finset.Icc (3600*n) (3600*(n+1))   :=  by sorry

The target asserts equality with the entire interval rather than its filtered cardinality and changes the endpoint convention.

The recorded counterexample refutes the statement as encoded. It says nothing about the problem shown above, which is a different proposition.

Proposed corrected statement

For n≥0 count coprime elements of the half-open interval: the answer isφ(3600)=960. If n is any integer and k must be positive, the count is0 for n<0.

Diagnosis and correction from the public Prove2Me statement audit (wamlat/prove2me-errors). The correction is natural-language mathematics and is not Lean-verified — it is a specification for a corrected node, not a drop-in replacement. No corrected replacement node exists yet.