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Mertens product upper bound (3.29), finite range 286≤x<700286 \le x < 700286≤x<700

Proved
TaoFivePrimes.rosser_schoenfeld_product_bound_finite

by chstdu · Sep 20, 2026 · Mathlib 0df444a (Lean v4.33.1)

analytic-number-theorymertens-theoremnumber-theory

For every real number xxx with 286≤x<700286 \le x < 700286≤x<700,

∏p≤x,  p primepp−1<eγ(log⁡x)(1+12log⁡2x),\prod_{p \le x, \; p \text{ prime}} \frac{p}{p-1} < e^{\gamma} (\log x)\left(1 + \frac{1}{2\log^2 x}\right),p≤x,p prime∏​p−1p​<eγ(logx)(1+2log2x1​),

where the product runs over the primes p≤xp \le xp≤x and γ\gammaγ denotes the Euler–Mascheroni constant.

This theorem is the finite-range leg of Rosser and Schoenfeld's proof of the Mertens product upper bound (3.29): in their proof of Theorem 8 (p. 70) the range x≤16,000x \le 16{,}000x≤16,000 is disposed of by direct tabulation, and the present statement covers the part 286≤x<700286 \le x < 700286≤x<700 of that tabulation for which no analytic substitute is available. It is provable by a finite certified computation: the left-hand side is a finite product of exact rational values, while the right-hand side can be bounded below using rational approximations to log⁡x\log xlogx and eγe^{\gamma}eγ.

Formalization Note. The product is written as ∏ p ∈ Nat.primesLE ⌊x⌋₊, (p : ℝ) / ((p : ℝ) - 1), the finite set of primes at most the natural floor of xxx, and the right-hand side is Real.exp Real.eulerMascheroniConstant * Real.log x * (1 + 1 / (2 * (Real.log x) ^ 2)), matching the parent target's formulation.

Preamble
import Mathlib.NumberTheory.PrimeCounting
import Mathlib.NumberTheory.Harmonic.EulerMascheroni
Formal statement
namespace TaoFivePrimes
theorem rosser_schoenfeld_product_bound_finite (x : ℝ) (hx : 286 ≤ x) (hx' : x < 700) :
    ∏ p ∈ Nat.primesLE ⌊x⌋₊, (p : ℝ) / ((p : ℝ) - 1) <
      Real.exp Real.eulerMascheroniConstant * Real.log x *
        (1 + 1 / (2 * (Real.log x) ^ 2)) := by sorry
end TaoFivePrimes
Source
J.B. Rosser, L. Schoenfeld, Approximate formulas for some functions of prime numbers, Illinois J. Math. 6 (1962), 64–94; §8, p. 70, Theorem 8, inequality (3.29), finite-range part of the proof (p. 87). https://doi.org/10.1215/ijm/1255631807

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