A counterexample to a subadditivity conjecture of Cohen for Sophie Germain cyclic numbers

Josué Alexander Ibarra

An integer $n\ge 1$ is cyclic if $\gcd (n,\phi (n))=1$ (equivalently, if every group of order $n$ is cyclic), and Sophie Germain cyclic if both $n$ and $2n+1$ are cyclic. Let $C_{\sigma }(N)$…