On square values of the product of the Euler totient and sum of divisors functions
Colloquium Mathematicum, Tome 130 (2013) no. 1, pp. 127-137.

Voir la notice de l'article provenant de la source Institute of Mathematics Polish Academy of Sciences

If $n$ is a positive integer such that $\phi (n)\sigma (n)=m^2$ for some positive integer $m$, then $m\le n$. We put $m=n-a$ and we study the positive integers $a$ arising in this way.
DOI : 10.4064/cm130-1-11
Keywords: positive integer phi sigma positive integer put n a study positive integers arising

Kevin Broughan 1 ; Kevin Ford 2 ; Florian Luca 3

1 Department of Mathematics University of Waikato Private Bag 3105, Hamilton, New Zealand
2 Department of Mathematics The University of Illinois at Urbana-Champaign Urbana 1409 West Green St. Champaign, IL 61801, U.S.A.
3 Fundación Marcos Moshinsky Instituto de Ciencias Nucleares UNAM Circuito Exterior, C.U., Apdo. Postal 70-543 México, D.F. 04510, Mexico
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Kevin Broughan; Kevin Ford; Florian Luca. On square values of the product of the Euler totient and sum of divisors functions. Colloquium Mathematicum, Tome 130 (2013) no. 1, pp. 127-137. doi : 10.4064/cm130-1-11. http://geodesic.mathdoc.fr/articles/10.4064/cm130-1-11/

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