On one example of a Nikishin system

The paper puts forward an example of a~Markov function $f=\mathrm{const}+\widehat{\sigma }$ such that the three functions $f,f^2$ and $f^3$ form a Nikishin system. A conjecture is proposed that there exists a~Markov function $f$ such that, for each $n\in \mathbb{N}$, the system $f,f^2,\dots ,f^n$ constitutes a~Nikishin system. Bibliography:~20~titles.