Positivity of the scaled factorial argument \(N_{10}\) to Exact formula for the scaled factorial argument \(N_{10}\)

LemmaPositivity of the scaled factorial argument \(N_{10}\)#✓fully proved

Let \(Q_9 = 210\) and, for natural numbers \(m\) and \(n\), let \(N_{10}(m, n) = 10 n \lfloor Q_9 / m \rfloor\). If \(n \ge 1\), \(m \ge 1\) and \(m\) divides \(Q_9\), then \(N_{10}(m, n) \ge 1\).

lemma N10_pos {m n : ℕ} (hn : 1 ≤ n) (hm1 : 1 ≤ m) (hd : m ∣ Q9) :
    1 ≤ N10m m n
Uses 3 · Used by 2

LemmaPositivity of the scaled argument N₉#✓fully proved

For natural numbers \(m\) and \(n\) with \(n \ge 1\), \(m \ge 1\) and \(m\) dividing \(Q_9 = 210\), the scaled factorial argument \(N_9(m, n) = 9n \lfloor Q_9 / m \rfloor\) satisfies \(N_9(m, n) \ge 1\).

lemma N9_pos {m n : ℕ} (hn : 1 ≤ n) (hm1 : 1 ≤ m) (hd : m ∣ Q9) :
    1 ≤ N9m m n
Uses 3 · Used by 2

LemmaPositivity of the scaled factorial argument \(N_1\)#✓fully proved

Let \(Q_9 = 210\) and, for natural numbers \(m\) and \(n\), let \(N_1(m, n) = n \lfloor Q_9 / m \rfloor\). If \(n \ge 1\), \(m \ge 1\) and \(m\) divides \(Q_9\), then \(N_1(m, n) \ge 1\).

lemma N1_pos {m n : ℕ} (hn : 1 ≤ n) (hm1 : 1 ≤ m) (hd : m ∣ Q9) :
    1 ≤ N1m m n
Uses 3 · Used by 2

LemmaUpper bound for the scaled factorial argument \(N_{10}\)#✓fully proved

Let \(Q_9 = 210\) and, for natural numbers \(m\) and \(n\), let \(N_{10}(m, n) = 10 n \lfloor Q_9 / m \rfloor\), where \(\lfloor Q_9 / 0 \rfloor\) is taken to be \(0\). Then \(N_{10}(m, n) \le 10 Q_9 n\) for all natural numbers \(m\) and \(n\).

lemma N10_le {m n : ℕ} : N10m m n ≤ 10 * Q9 * n
Uses 2 · Used by 3

LemmaUpper bound for the scaled factorial argument \(N_9\)#✓fully proved

Let \(Q_9 = 210\) and, for natural numbers \(m\) and \(n\), let \(N_9(m, n) = 9 n \lfloor Q_9 / m \rfloor\), where \(\lfloor Q_9 / 0 \rfloor\) is taken to be \(0\). Then \(N_9(m, n) \le 10 Q_9 n\) for all natural numbers \(m\) and \(n\).

lemma N9_le {m n : ℕ} : N9m m n ≤ 10 * Q9 * n
Uses 2 · Used by 2

LemmaUpper bound for the scaled factorial argument \(N_1\)#✓fully proved

Let \(Q_9 = 210\) and, for natural numbers \(m\) and \(n\), let \(N_1(m, n) = n \lfloor Q_9 / m \rfloor\), where \(\lfloor Q_9 / 0 \rfloor\) is taken to be \(0\). Then \(N_1(m, n) \le 10 Q_9 n\) for all natural numbers \(m\) and \(n\).

lemma N1_le {m n : ℕ} : N1m m n ≤ 10 * Q9 * n
Uses 2 · Used by 2

LemmaN₁₀ splits as N₉ + N₁#✓fully proved

For natural numbers \(m\) and \(n\) with \(m \ge 1\) and \(m\) dividing \(Q_9 = 210\), write \(N_k(m, n) = kn \lfloor Q_9 / m \rfloor\) for \(k = 1, 9, 10\). Then \(N_{10}(m, n) = N_9(m, n) + N_1(m, n)\).

lemma Nadd9 {m n : ℕ} (hm1 : 1 ≤ m) (hd : m ∣ Q9) :
    N10m m n = N9m m n + N1m m n
Uses 4 · Used by 1

LemmaFactorial divisibility behind ratio₉#✓fully proved

For natural numbers \(m\) and \(n\) with \(m \ge 1\) and \(m\) dividing \(Q_9 = 210\), write \(N_k(m, n) = kn \lfloor Q_9 / m \rfloor\) for \(k = 1, 9, 10\). Then \(N_9(m, n)! \cdot N_1(m, n)!\) divides \(N_{10}(m, n)!\).

lemma ratio9_dvd (m n : ℕ) (hm1 : 1 ≤ m) (hd : m ∣ Q9) :
    (N9m m n)! * (N1m m n)! ∣ (N10m m n)!
Uses 5 · Used by 4

LemmaPositivity of ratio₉#✓fully proved

For natural numbers \(m\) and \(n\) with \(n \ge 1\), \(m \ge 1\) and \(m\) dividing \(Q_9 = 210\), the binomial factor \(\mathrm{ratio}_9(m, n) = N_{10}(m, n)! / (N_9(m, n)! \cdot N_1(m, n)!)\) is positive, where \(N_k(m, n) = kn \lfloor Q_9 / m \rfloor\) for \(k = 1, 9, 10\).

lemma ratio9_pos (m n : ℕ) (_hn : 1 ≤ n) (hm1 : 1 ≤ m) (hd : m ∣ Q9) :
    0 < ratio9 m n
Uses 6 · Used by 1

LemmaLogarithm of the binomial factor#✓fully proved

Let \(m\) and \(n\) be natural numbers with \(n \ge 1\), \(m \ge 1\) and \(m \mid 210\), and put \(k = 210/m\). Then

\[\log \frac{(10nk)!}{(9nk)!\,(nk)!} = \log (10nk)! - \log (9nk)! - \log (nk)!.\]
lemma log_ratio9 (m n : ℕ) (_hn : 1 ≤ n) (hm1 : 1 ≤ m) (hd : m ∣ Q9) :
    Real.log ((ratio9 m n : ℕ) : ℝ)
      = Real.log (((N10m m n)!) : ℝ) - Real.log (((N9m m n)!) : ℝ)
        - Real.log (((N1m m n)!) : ℝ)
Uses 6 · Used by 1

LemmaMöbius reciprocal sum over the divisors of 210, in the rationals#✓fully proved

Let \(w_9\) be the table of pairs \((d, \mu(d))\), where \(d\) runs over the divisors of \(210\) and \(\mu\) is the Möbius function. Then the sum of \(\mu(d)/d\) over the pairs of \(w_9\), computed in \(\mathbb{Q}\), is \(8/35\); that is, \(\sum_{d \mid 210} \mu(d)/d = 8/35\).

lemma w9_mu_sum_Q : w9.toFinset.sum (fun q : ℕ × ℤ => (q.2 : ℚ) / (q.1 : ℚ)) = 8/35
Uses 3 · Used by 1

LemmaMöbius reciprocal sum over the divisors of 210, in the reals#✓fully proved

Let \(w_9\) be the table of pairs \((d, \mu(d))\), where \(d\) runs over the divisors of \(210\) and \(\mu\) is the Möbius function. Then the sum of \(\mu(d)/d\) over the pairs of \(w_9\), computed in \(\mathbb{R}\), is \(8/35\); that is, \(\sum_{d \mid 210} \mu(d)/d = 8/35\).

lemma w9_mu_sum_R : w9.toFinset.sum (fun q : ℕ × ℤ => (q.2 : ℝ) / (q.1 : ℝ)) = 8/35
Uses 2 · Used by 1

LemmaLower bound for \(\log N!\)#✓fully proved

For every natural number \(N \ge 1\), \(N \log N - N + 1 \le \log N!\).

lemma log_fact_lower {N : ℕ} (hN : 1 ≤ N) :
    (N : ℝ) * Real.log (N : ℝ) - (N : ℝ) + 1 ≤ Real.log ((N ! : ℕ) : ℝ)
Uses 1 · Used by 1

LemmaUpper bound for \(\log N!\)#✓fully proved

For every natural number \(N \ge 1\), \(\log N! \le (N + 1) \log N - N + 1\).

lemma log_fact_upper {N : ℕ} (hN : 1 ≤ N) :
    Real.log ((N ! : ℕ) : ℝ) ≤ ((N : ℝ)+1) * Real.log (N : ℝ) - (N : ℝ) + 1
Uses 1 · Used by 1

DefinitionMain Stirling term#✓fully proved

For a real number \(x\), \(f_{\mathrm{main}}(x) = x \log x - x\).

This is the main term of Stirling's approximation to \(\log x!\).

noncomputable def fmain (x : ℝ) : ℝ := x * Real.log x - x
Used by 4

LemmaTermwise Stirling lower bound in Breusch's argument#✓fully proved

Let \((d, \varepsilon)\) be a pair in the Möbius divisor table \(W_9\) for \(Q_9 = 210\) and let \(n \ge 1\) be a natural number. Write \(q = \lfloor Q_9 / d \rfloor\) for the natural-number quotient, and let \(A = N_{10}(d, n) = 10nq\), \(B = N_9(d, n) = 9nq\) and \(C = N_1(d, n) = nq\) be the scaled factorial arguments and \(f_{\mathrm{main}}(x) = x \log x - x\) the main Stirling term. Then \(\varepsilon (\log A! - \log B! - \log C!) \ge \varepsilon (f_{\mathrm{main}}(A) - f_{\mathrm{main}}(B) - f_{\mathrm{main}}(C)) - (1 + \log A + \log B + \log C)\).

lemma logF9_term_lower (q : ℕ × ℤ) (hq : q ∈ w9) (n : ℕ) (hn : 1 ≤ n) :
    (q.2 : ℝ) * (Real.log (((N10m q.1 n)!) : ℝ) - Real.log (((N9m q.1 n)!) : ℝ)
      - Real.log (((N1m q.1 n)!) : ℝ))
    ≥ (q.2 : ℝ) * (fmain ((N10m q.1 n : ℕ) : ℝ) - fmain ((N9m q.1 n : ℕ) : ℝ)
      - fmain ((N1m q.1 n : ℕ) : ℝ))
      - (1 + Real.log ((N10m q.1 n : ℕ) : ℝ) + Real.log ((N9m q.1 n : ℕ) : ℝ)
        + Real.log ((N1m q.1 n : ℕ) : ℝ))
Uses 14 · Used by 1

LemmaDivisors of 210 divide multiples of 210#✓fully proved

Let \(w_9\) be the table of divisors \(d\) of \(Q_9 = 210\) paired with their Möbius values. If \(C\) is a natural number with \(Q_9 \mid C\), then for every pair \((d, \varepsilon)\) in \(w_9\) and every natural number \(n\), \(d \mid C n\).

lemma CNdvd9 (C : ℕ) (hC : Q9 ∣ C) (q : ℕ × ℤ) (hq : q ∈ w9) (n : ℕ) :
    q.1 ∣ C * n
Uses 3 · Used by 1

DefinitionThe constant \(K_9\)#✓fully proved

Let \(w_9\) be the table of divisors \(d\) of \(Q_9 = 210\) paired with their Möbius values \(\varepsilon\). Then

\[K_9 = \sum_{(d, \varepsilon) \in w_9} \frac{\varepsilon \log d}{d}.\]

It comes from the \(\log d\) terms in the closed form of \(\sum_{(d, \varepsilon) \in w_9} \varepsilon f(N/d)\) with \(f(x) = x \log x - x\), for \(N\) a multiple of \(210\).

noncomputable def K9 : ℝ :=
  w9.toFinset.sum (fun q : ℕ × ℤ => (q.2 : ℝ) * Real.log (q.1 : ℝ) / (q.1 : ℝ))
Uses 1 · Used by 2

LemmaClosed form of the Möbius-weighted main-term sum#✓fully proved

Let \(w_9\) be the table of pairs \((d, \mu(d))\) for the divisors \(d\) of \(210\), let \(f(x) = x \log x - x\), and let \(K_9 = \sum_{(d, \mu(d)) \in w_9} \mu(d) \log d / d\). For natural numbers \(C > 0\) and \(n \ge 1\) with \(210 \mid C\), writing \(N = Cn\) (so that \(N/d\) is an integer for each \(d\) in \(w_9\)), we have \(\sum_{(d, \mu(d)) \in w_9} \mu(d) f(N/d) = \frac{8}{35} N (\log N - 1) - K_9 N\).

lemma Z9_value (C n : ℕ) (hC0 : 0 < C) (hn : 1 ≤ n) (hC : Q9 ∣ C) :
    w9.toFinset.sum (fun q : ℕ × ℤ => (q.2 : ℝ) * fmain (((C*n/q.1 : ℕ)) : ℝ))
    = (8/35) * ((C*n : ℕ):ℝ) * (Real.log ((C*n : ℕ):ℝ) - 1)
      - K9 * ((C*n : ℕ):ℝ)
Uses 7 · Used by 1

LemmaExact formula for the scaled factorial argument \(N_{10}\)#✓fully proved

Let \(Q_9 = 210\) and, for natural numbers \(m\) and \(n\), let \(N_{10}(m, n) = 10 n \lfloor Q_9 / m \rfloor\). If \(m \ge 1\) and \(m\) divides \(Q_9\), then \(N_{10}(m, n) = \lfloor 10 Q_9 n / m \rfloor\).

lemma N10_eq {m n : ℕ} (hm1 : 1 ≤ m) (hd : m ∣ Q9) : N10m m n = 10*Q9*n/m
Uses 2 · Used by 2
20 fully proved

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