Proofs, generalizations and analogs of Menon’s identity: a survey

Menon’s identity states that for every positive integer n one has ∑ (a − 1, n) = φ (n)τ(n), where a runs through a reduced residue system (mod n), (a − 1, n) stands for the greatest common divisor of a − 1 and n, φ(n) is Euler’s totient function, and τ(n) is the number of divisors of n. Menon’s iden...

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Main Author: Tóth László
Format: Article
Language:English
Published: Sciendo 2023-11-01
Series:Acta Universitatis Sapientiae: Mathematica
Subjects:
Online Access:https://doi.org/10.2478/ausm-2023-0009
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author Tóth László
author_facet Tóth László
author_sort Tóth László
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description Menon’s identity states that for every positive integer n one has ∑ (a − 1, n) = φ (n)τ(n), where a runs through a reduced residue system (mod n), (a − 1, n) stands for the greatest common divisor of a − 1 and n, φ(n) is Euler’s totient function, and τ(n) is the number of divisors of n. Menon’s identity has been the subject of many research papers, also in the last years. We present detailed, self contained proofs of this identity by using different methods, and point out those that we could not identify in the literature. We survey the generalizations and analogs, and overview the results and proofs given by Menon in his original paper. Some historical remarks and an updated list of references are included as well.
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spelling doaj.art-027787e7f41048b6a915661f3d5c2c562023-11-20T07:17:10ZengSciendoActa Universitatis Sapientiae: Mathematica2066-77522023-11-0115114219710.2478/ausm-2023-0009Proofs, generalizations and analogs of Menon’s identity: a surveyTóth László01Department of Mathematics, University of Pécs, Ifjúságútja 6, 7624 Pécs, HungaryMenon’s identity states that for every positive integer n one has ∑ (a − 1, n) = φ (n)τ(n), where a runs through a reduced residue system (mod n), (a − 1, n) stands for the greatest common divisor of a − 1 and n, φ(n) is Euler’s totient function, and τ(n) is the number of divisors of n. Menon’s identity has been the subject of many research papers, also in the last years. We present detailed, self contained proofs of this identity by using different methods, and point out those that we could not identify in the literature. We survey the generalizations and analogs, and overview the results and proofs given by Menon in his original paper. Some historical remarks and an updated list of references are included as well.https://doi.org/10.2478/ausm-2023-0009menon’s identityarithmetic functioneuler’s functionramanujan’s sumdirichlet characterdirichlet convolutionunitary convolutiongroup actionorbit counting lemman-even functionfinite fourier representation11a0711a2522f05
spellingShingle Tóth László
Proofs, generalizations and analogs of Menon’s identity: a survey
Acta Universitatis Sapientiae: Mathematica
menon’s identity
arithmetic function
euler’s function
ramanujan’s sum
dirichlet character
dirichlet convolution
unitary convolution
group action
orbit counting lemma
n-even function
finite fourier representation
11a07
11a25
22f05
title Proofs, generalizations and analogs of Menon’s identity: a survey
title_full Proofs, generalizations and analogs of Menon’s identity: a survey
title_fullStr Proofs, generalizations and analogs of Menon’s identity: a survey
title_full_unstemmed Proofs, generalizations and analogs of Menon’s identity: a survey
title_short Proofs, generalizations and analogs of Menon’s identity: a survey
title_sort proofs generalizations and analogs of menon s identity a survey
topic menon’s identity
arithmetic function
euler’s function
ramanujan’s sum
dirichlet character
dirichlet convolution
unitary convolution
group action
orbit counting lemma
n-even function
finite fourier representation
11a07
11a25
22f05
url https://doi.org/10.2478/ausm-2023-0009
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