Resumen de Arithmetic properties of $\varphi(n)/\lambda(n)$ and the structure of the multiplicative group modulo $n$
William D. Banks, Florian Luca, Igor E. Shparlinski
For a positive integer $n$, we let $\varphi(n)$ and $\lambda(n)$ denote the Euler function and the Carmichael function, respectively. We define $\xi(n)$ as the ratio $\varphi(n)/\lambda(n)$ and study various arithmetic properties of $\xi(n)$.
