On square values of the product of the Euler totient and sum of divisors functions
Volume 130 / 2013
Colloquium Mathematicum 130 (2013), 127-137
MSC: Primary 11A41.
DOI: 10.4064/cm130-1-11
Abstract
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.
