Abstract:
It is proved that for every $n\geqslant1$, the group $\operatorname{Out}(F_n)$ is embedded in the group $\operatorname{Out}(F_m)$ with $m=1+(n-1)k^n$, where $k$ is an arbitrary natural number coprime to $n-1$.
Keywords:group of outer automorphisms, free group.