On the equation \(\varphi(| x^m+y^m|)=| x^n+ y^n|\)
For any positive integer \(k\), let \(\varphi(k)\) be the Euler totient function of \(k\). All nontrivial integer solutions \((x,y,m,n)\) of the diophantine equation \(\varphi(| x^m+y^m|)=| x^n+y^n|\) are found.
scientific article; zbMATH DE number 1275963