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Erdős ProblemsNumber theory

Erdős Problem 700: Iii

Let f(n)=min1<kn/2gcd(n,(nk))f(n) = \min_{1 < k \le n/2} \gcd(n, \binom{n}{k}). (c)* Is it true that, for every composite nn, f(n)An/(logn)Af(n) \ll_A n/(\log n)^A for every A>0A > 0?

Mathematical statement

Let f(n)=min1<kn/2gcd(n,(nk))f(n) = \min_{1 < k \le n/2} \gcd(n, \binom{n}{k}). (c)* Is it true that, for every composite nn, f(n)An/(logn)Af(n) \ll_A n/(\log n)^A for every A>0A > 0?

Erdős–Szekeres [ErSz78] prove the weaker bound f(n)(1+o(1))n/lognf(n) \le (1 + o(1)) n/\log n (the case A=1A = 1). Here f(n)An/(logn)Af(n) \ll_A n/(\log n)^A is spelled out as: for every A > 0 there is a constant C (depending on A) with f(n) ≤ C · n/(log n)^A for every composite n.

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_700.parts.iii

Canonical source
Complete statement target, proof intentionally absentLean 4
theorem erdos_700.parts.iii :    answer(sorry)  ( A : , 0 < A   C : , 0 < C   n : , ¬ n.Prime  1 < n       (f n : )  C * (n : ) / (Real.log n) ^ A) := 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