JP Journal of Algebra, Number Theory and Applications

The JP Journal of Algebra, Number Theory and Applications is a prestigious international journal indexed in the Emerging Sources Citation Index (ESCI). It publishes original research papers, both theoretical and applied in nature, in various branches of algebra and number theory. The journal also welcomes survey articles that contribute to the advancement of these fields.

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ON THE INVERSE IMAGES OF THE EULER FUNCTION $\varphi$

Authors

  • Atsushi Yamagami
  • Yudai Sumiya

Keywords:

the Euler function, inverse image.

DOI:

https://doi.org/10.17654/0972555524021

Abstract

Thevalue $\varphi(m)$ for any positive integer $m$ of the Euler function $\varphi$ is equal to the number of integers $1 \leq a \leq m$ such that $\operatorname{gcd}(a, m)=1$.

In this article, based on data about the inverse image $\varphi^{-1}(n)$ for any even $2 \leq n \leq 5000$ calculated by the second author, we propose a conjecture asserting that for any even $n$, if the set $\varphi^{-1}(n)_{\text {o }}$ of odd inverse images of $n$ is not empty, then the minimum of $\varphi^{-1}(n)$ should be odd. Then we obtain some partial positive results on this conjecture. Moreover, we give some sufficient conditions for $n$ such that $\varphi^{-1}(n)$ or $\varphi^{-1}(n)_0$ is empty.

Received: February 13, 2024
Accepted: April 18, 2024

References

R. D. Carmichael, On Euler’s -function, Bull. Amer. Math. Soc. 13 (1907), 241 243.

R. D. Carmichael, Note on Euler’s -function, Bull. Amer. Math. Soc. 28 (1922), 109-110.

K. Ford, The number of solutions of Annals of Mathematics 150 (1999), 1-29.

W. Keller, Prime factors of Fermat numbers and complete factoring status, http://www.prothsearch.com/fermat.html

N. S. Mendelsohn, The equation Mathematics Magazine 49 (1976), 37 39.

A. Schinzel, Sur l’equation Elem. Math. 11 (1956), 75-78.

A. Schinzel, Sur un probleme concernant la function Czechoslovak Mathematical Journal 6 (1956), 164-165.

M. W. Sierpinski, Voir solution du problem 230, Elem. Math. 11 (1956), 37.

Published

2024-05-23

Issue

Section

Articles

How to Cite

ON THE INVERSE IMAGES OF THE EULER FUNCTION $\varphi$. (2024). JP Journal of Algebra, Number Theory and Applications, 63(4), 335-362. https://doi.org/10.17654/0972555524021

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