Bala A347854: integrality at every natural index
Abstract
Bala A347854 integrality.
Definition 1.1 (ffact).
Formalization. D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.ffact (✓ std3).
Citation. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
OEIS A347854, COMMENTS (unpaginated): “Fractional factorials are defined using the Gamma function; for example, (n/2)! := Gamma(1 + n/2).” The function ffact uses a real argument.
Definition 1.2 (a).
Formalization. D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.a (✓ std3).
Citation. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
OEIS A347854, NAME (unpaginated): “a(n) = (6n)!/((3n)!(2n)!) * (n/2)!/(3*n/2)!.” Natural factorials are cast to the reals; fractional factorials use ffact.
Definition 1.3 (claim).
Formalization. D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.claim (✓ std3).
Citation. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
OEIS A347854, COMMENTS (unpaginated): “The sequence is conjectured to be integral.” Integrality means that for every natural index, including zero, the value is the cast of an integer.
Theorem 1.4 (mul_div_reduce).
Proof. Machine-checked in Lean as D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.mul_div_reduce (✓ std3). ∎
Source. Repository-derived.
Acknowledgement. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
Natural floor division separates a multiple of the quotient from the contribution of the remainder. Nat.div and Nat.mod denote natural division and remainder.
Theorem 1.5 (grid_floor).
Proof. Machine-checked in Lean as D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.grid_floor (✓ std3). ∎
Source. Repository-derived.
Acknowledgement. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
When L equals c times the positive integer d, division of the L-scaled numerator and then by d gives the c-scaled quotient. Nat.div denotes natural floor division.
Theorem 1.6 (factorial_prod_dvd_of_floor).
Proof. Machine-checked in Lean as D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.factorial_prod_dvd_of_floor (✓ std3). ∎
Source. Repository-derived.
Acknowledgement. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
If every positive-modulus floor sum of B is at most the corresponding sum of A, the product of the factorials in B divides that in A. Nat.div denotes natural floor division. Legendre valuations turn the floor inequalities into divisibility.
Theorem 1.7 (quotient_cast_integral).
Proof. Machine-checked in Lean as D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.quotient_cast_integral (✓ std3). ∎
Source. Repository-derived.
Acknowledgement. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
A quotient of natural numbers with a nonzero denominator that divides the numerator is the real cast of an integer.
Definition 1.8 (h856).
Formalization. D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.h856 (✓ std3).
Citation. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
The integer-valued floor defect for this factorial ratio. Nat.div denotes natural floor division before the cast to the integers. The associated Landau function occurs in Bober, Table 2.
Theorem 1.9 (h856_nonneg).
Proof. Machine-checked in Lean as D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.h856_nonneg (✓ std3). ∎
Citation. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
This floor defect is nonnegative at every natural numerator and positive modulus. Reduction modulo the modulus and subdivision at the floor breakpoints gives the inequality.
Definition 1.10 (h857).
Formalization. D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.h857 (✓ std3).
Citation. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
The integer-valued floor defect for this factorial ratio. Nat.div denotes natural floor division before the cast to the integers. The associated Landau function occurs in Bober, Table 2.
Theorem 1.11 (h857_nonneg).
Proof. Machine-checked in Lean as D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.h857_nonneg (✓ std3). ∎
Citation. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
This floor defect is nonnegative at every natural numerator and positive modulus. Reduction modulo the modulus and subdivision at the floor breakpoints gives the inequality.
Definition 1.12 (h858).
Formalization. D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.h858 (✓ std3).
Citation. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
The integer-valued floor defect for this factorial ratio. Nat.div denotes natural floor division before the cast to the integers. The associated Landau function occurs in Bober, Table 2.
Theorem 1.13 (h858_nonneg).
Proof. Machine-checked in Lean as D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.h858_nonneg (✓ std3). ∎
Citation. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
This floor defect is nonnegative at every natural numerator and positive modulus. Reduction modulo the modulus and subdivision at the floor breakpoints gives the inequality.
Definition 1.14 (k856).
Formalization. D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.k856 (✓ std3).
Citation. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
The integer-valued floor defect for this factorial ratio. Nat.div denotes natural floor division before the cast to the integers. The associated Landau function occurs in Bober, Table 2.
Theorem 1.15 (k856_nonneg).
Proof. Machine-checked in Lean as D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.k856_nonneg (✓ std3). ∎
Citation. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
This floor defect is nonnegative at every natural numerator and positive modulus. Reduction modulo the modulus and subdivision at the floor breakpoints gives the inequality.
Definition 1.16 (k857).
Formalization. D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.k857 (✓ std3).
Citation. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
The integer-valued floor defect for this factorial ratio. Nat.div denotes natural floor division before the cast to the integers. The associated Landau function occurs in Bober, Table 2.
Theorem 1.17 (k857_nonneg).
Proof. Machine-checked in Lean as D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.k857_nonneg (✓ std3). ∎
Citation. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
This floor defect is nonnegative at every natural numerator and positive modulus. Reduction modulo the modulus and subdivision at the floor breakpoints gives the inequality.
Definition 1.18 (k858).
Formalization. D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.k858 (✓ std3).
Citation. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
The integer-valued floor defect for this factorial ratio. Nat.div denotes natural floor division before the cast to the integers. The associated Landau function occurs in Bober, Table 2.
Theorem 1.19 (k858_nonneg).
Proof. Machine-checked in Lean as D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.k858_nonneg (✓ std3). ∎
Citation. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
This floor defect is nonnegative at every natural numerator and positive modulus. Reduction modulo the modulus and subdivision at the floor breakpoints gives the inequality.
Theorem 1.20 (gamma_nat).
Proof. Machine-checked in Lean as D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.gamma_nat (✓ std3). ∎
Source. Repository-derived.
Acknowledgement. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
The Gamma value at one plus a natural number equals its factorial.
Theorem 1.21 (gamma_ratio_half).
Proof. Machine-checked in Lean as D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.gamma_ratio_half (✓ std3). ∎
Source. Repository-derived.
Acknowledgement. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
For odd natural r ≤ s, the quotient of the two half-integer Gamma values is a factorial ratio times 2 raised to s−r. Nat.div denotes natural floor division in the factorial arguments.
Theorem 1.22 (gamma_third_ratio).
Proof. Machine-checked in Lean as D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.gamma_third_ratio (✓ std3). ∎
Source. Repository-derived.
Acknowledgement. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
Applying the Gamma recurrence n times expresses the third-index quotient as 3 to the power n divided by a product of n positive linear factors.
Theorem 1.23 (even_dvd).
Proof. Machine-checked in Lean as D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.even_dvd (✓ std3). ∎
Source. Repository-derived.
Acknowledgement. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
The denominator of the even-index factorial expression divides its numerator. This supplies both the half-index sequence and the third-index sequence at multiples of three.
Theorem 1.24 (result).
Proof. Machine-checked in Lean as D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.result (✓ std3). ∎
Resolves. Problems/oeis-a347854-bala-half-index-integrality (proved) by D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.result.
Source. Repository-derived.
Acknowledgement. Peter Bala (2021). OEIS A347854–A347858: fractional factorial ratios. URL: https://oeis.org/A347854.
Commentary.
Every natural index has an integer value. Reduction to factorial quotients and comparison of prime valuations give an integer cast.
References
- Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.a - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.claim - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.even_dvd - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.factorial_prod_dvd_of_floor - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.ffact - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.gamma_nat - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.gamma_ratio_half - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.gamma_third_ratio - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.grid_floor - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.h856 - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.h856_nonneg - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.h857 - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.h857_nonneg - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.h858 - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.h858_nonneg - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.k856 - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.k856_nonneg - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.k857 - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.k857_nonneg - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.k858 - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.k858_nonneg - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.mul_div_reduce - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.quotient_cast_integral - Truth anchor:
D5/S3/Arith/FactorialRatio/OeisA347854BalaHalfIndexIntegral.result