Exact formula for the scaled factorial argument \(N_9\) to Power bound for the multinomial coefficient \(M(t)\), small \(t\)

LemmaExact formula for the scaled factorial argument \(N_9\)#✓fully proved

Let \(Q_9 = 210\) and, for natural numbers \(m\) and \(n\), let \(N_9(m, n) = 9 n \lfloor Q_9 / m \rfloor\). If \(m \ge 1\) and \(m\) divides \(Q_9\), then \(N_9(m, n) = \lfloor 9 Q_9 n / m \rfloor\).

lemma N9_eq {m n : ℕ} (hm1 : 1 ≤ m) (hd : m ∣ Q9) : N9m m n = 9*Q9*n/m
Uses 2 · Used by 2

LemmaExact formula for the scaled factorial argument \(N_1\)#✓fully proved

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

lemma N1_eq {m n : ℕ} (hm1 : 1 ≤ m) (hd : m ∣ Q9) : N1m m n = Q9*n/m
Uses 2 · Used by 2

LemmaCombined main term of the Möbius-weighted Stirling sums#✓fully proved

Let \(w_9\) be the table of pairs \((d, \mu(d))\) for the divisors \(d\) of \(210\), and let \(f(x) = x \log x - x\). For every natural number \(n \ge 1\), writing \(N = 210n\) (so that \(N/d\) is an integer for each \(d\) in \(w_9\)), we have \(\sum_{(d, \mu(d)) \in w_9} \mu(d) \bigl(f(10N/d) - f(9N/d) - f(N/d)\bigr) = 48 n (10 \log 10 - 9 \log 9)\).

lemma Z9_combined (n : ℕ) (hn : 1 ≤ n) :
    w9.toFinset.sum (fun q : ℕ×ℤ => (q.2:ℝ) * (fmain (((10*Q9*n/q.1:ℕ)):ℝ)
      - fmain (((9*Q9*n/q.1:ℕ)):ℝ) - fmain (((Q9*n/q.1:ℕ)):ℝ)))
    = 48 * (n:ℝ) * (10 * Real.log 10 - 9 * Real.log 9)
Uses 7 · Used by 1

LemmaLower bound for \(\log F_9(n)\)#✓fully proved

Let \(w_9\) be the table of divisors \(d\) of \(Q_9 = 210\) paired with their Möbius values \(\varepsilon\), and for a natural number \(n\) let

\[\log F_9(n) = \sum_{(d, \varepsilon) \in w_9} \varepsilon \log \frac{(10 n k_d)!}{(9 n k_d)!\,(n k_d)!}, \qquad k_d = 210/d.\]

Then for every natural number \(n \ge 1\),

\[48 n (10 \log 10 - 9 \log 9) - 16 - 48 \log(2100 n) \le \log F_9(n).\]
lemma logF9_lower (n : ℕ) (hn : 1 ≤ n) :
    48 * (n:ℝ) * (10 * Real.log 10 - 9 * Real.log 9) - 16
      - 48 * Real.log ((2100*n:ℕ):ℝ) ≤ logF9 n
Uses 25 · Used by 1

LemmaExtending the primorial bound leftward across an interval#✓fully proved

Let \(a \le m \le b\) be natural numbers, and write \(n\#\) for the primorial of \(n\) (the product of all primes \(p \le n\)). If \(10^a \cdot b\# \le 34^a\), then \(10^m \cdot m\# \le 34^m\).

lemma theta34_of_interval {lo hi m : ℕ} (hlo : lo ≤ m) (hhi : m ≤ hi)
    (hend : 10 ^ lo * primorial hi ≤ 34 ^ lo) :
    10 ^ m * primorial m ≤ 34 ^ m
Used by 1

DefinitionThe multinomial coefficient \(M(t)\) for the 3.4 primorial bound#✓fully proved

For a natural number \(t\), \(M(t) = \frac{(6t)!}{(3t)!\,(2t)!\,t!}\), defined as the quotient of \((6t)!\) by \((3t)!\,(2t)!\,t!\) in natural-number division.

def M34 (t : ℕ) : ℕ := (6*t)! / ((3*t)! * (2*t)! * t !)
Used by 10

LemmaFactorial divisibility behind the multinomial coefficient#✓fully proved

For every natural number \(t\), the product \((3t)!\,(2t)!\,t!\) divides \((6t)!\).

lemma M34_dvd (t : ℕ) : (3*t)! * (2*t)! * t ! ∣ (6*t)!
Used by 2

LemmaPositivity of the multinomial coefficient \(M(t)\)#✓fully proved

Let \(M(t)\) be the natural-number quotient of \((6t)!\) by \((3t)!\,(2t)!\,t!\). For every natural number \(t\), \(M(t) > 0\).

lemma M34_pos (t : ℕ) : 0 < M34 t
Uses 2 · Used by 2

LemmaCleared-denominator identity for the multinomial coefficient \(M(t)\)#✓fully proved

Let \(M(t)\) be the natural-number quotient of \((6t)!\) by \((3t)!\,(2t)!\,t!\). For every natural number \(t\), \(M(t) \cdot \big((3t)!\,(2t)!\,t!\big) = (6t)!\).

lemma M34_eq_mul (t : ℕ) : M34 t * ((3*t)! * (2*t)! * t !) = (6*t)!
Uses 2 · Used by 2

LemmaThe multinomial coefficient \(M(t)\) as a product of binomial coefficients#✓fully proved

Let \(M(t) = \frac{(6t)!}{(3t)!\,(2t)!\,t!}\). For every natural number \(t\), \(M(t) = \binom{6t}{3t} \binom{3t}{t}\).

lemma M34_eq_choose_mul (t : ℕ) : M34 t = Nat.choose (6*t) (3*t) * Nat.choose (3*t) t
Uses 2 · Used by 1

LemmaHalf-power bound for the central binomial coefficient#✓fully proved

For every natural number \(m \ge 1\), \(\binom{2m}{m} \le 2^{2m-1}\).

lemma choose_middle_half {m : ℕ} (hm : 1 ≤ m) : Nat.choose (2*m) m ≤ 2^(2*m-1)
Used by 1

LemmaMultinomial bound for \((3t)!\)#✓fully proved

For every natural number \(t\), \((3t)! \le 3^{3t} (t!)^3\).

lemma multinomial3_le (t : ℕ) : (3*t)! ≤ 3^(3*t) * (t !)^3
Used by 1

LemmaBinomial factorization of the factorial of a multiple of three#✓fully proved

For every natural number \(t\), \(\binom{3t}{t} \binom{2t}{t} (t!)^3 = (3t)!\).

lemma choose3_mul_choose2 (t : ℕ) :
    Nat.choose (3*t) t * Nat.choose (2*t) t * (t !)^3 = (3*t)!
Used by 1

LemmaFour-power lower bound for the central binomial coefficient#✓fully proved

For every natural number \(t\), \(4^t \le (2t+1)\binom{2t}{t}\).

lemma four_pow_le (t : ℕ) : 4^t ≤ (2*t+1) * Nat.choose (2*t) t
Used by 1

LemmaKey estimate for the multinomial coefficient \(M(t)\)#✓fully proved

Let \(M(t) = \frac{(6t)!}{(3t)!\,(2t)!\,t!}\). For every natural number \(t \ge 1\), \(2\,M(t) \le 432^t \, (2t + 1)\).

lemma M34_key (t : ℕ) (ht : 1 ≤ t) : 2 * M34 t ≤ 432^t * (2*t+1)
Uses 6 · Used by 1

LemmaBase case of the threshold inequality#✓fully proved

The inequality \(10^{1145} \cdot 432^{230} \cdot 461 \le 2 \cdot 34^{1145}\) holds; this is the inequality \(10^{5t-5} \cdot 432^{t} \cdot (2t+1) \le 2 \cdot 34^{5t-5}\) at \(t = 230\).

Checked by direct computation.

lemma P34_base : 10^(5*230-5) * 432^230 * (2*230+1) ≤ 2 * 34^(5*230-5)
Used by 1

LemmaInduction step of the threshold inequality#✓fully proved

Let \(t \ge 230\) be a natural number. If \(10^{5t-5} \cdot 432^{t} \cdot (2t+1) \le 2 \cdot 34^{5t-5}\), then \(10^{5t} \cdot 432^{t+1} \cdot (2t+3) \le 2 \cdot 34^{5t}\), which is the same inequality with \(t+1\) in place of \(t\).

lemma P34_step (t : ℕ) (ht : 230 ≤ t)
    (ih : 10 ^ (5 * t - 5) * 432 ^ t * (2 * t + 1) ≤ 2 * 34 ^ (5 * t - 5)) :
    10 ^ (5 * (t + 1) - 5) * 432 ^ (t + 1) * (2 * (t + 1) + 1) ≤ 2 * 34 ^ (5 * (t + 1) - 5)
Used by 1

LemmaThreshold inequality for the multinomial bound#✓fully proved

For every natural number \(t \ge 230\), \(10^{5t-5} \cdot 432^{t} \cdot (2t+1) \le 2 \cdot 34^{5t-5}\).

lemma P34 (t : ℕ) (ht : 230 ≤ t) :
    10^(5*t-5) * 432^t * (2*t+1) ≤ 2 * 34^(5*t-5)
Uses 2 · Used by 1

LemmaPower bound for the multinomial coefficient \(M(t)\), large \(t\)#✓fully proved

Let \(M(t) = \frac{(6t)!}{(3t)!\,(2t)!\,t!}\). For every natural number \(t \ge 230\), \(10^{5t-5} \cdot M(t) \le 34^{5t-5}\), that is, \(M(t) \le 3.4^{5t-5}\).

lemma M34_bound_large (t : ℕ) (ht : 230 ≤ t) : 10^(5*t-5) * M34 t ≤ 34^(5*t-5)
Uses 3 · Used by 1

LemmaPower bound for the multinomial coefficient \(M(t)\), small \(t\)#✓fully proved

Let \(M(t) = \frac{(6t)!}{(3t)!\,(2t)!\,t!}\). For every natural number \(k < 207\), writing \(t = 23 + k\) (so \(23 \le t < 230\)), we have \(10^{5t-5} \cdot M(t) \le 34^{5t-5}\).

The finitely many cases are checked by direct computation.

lemma M34_bound_small : ∀ k < 207,
    10 ^ (5 * (23 + k) - 5) * M34 (23 + k) ≤ 34 ^ (5 * (23 + k) - 5)
Uses 1 · Used by 1
20 fully proved

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