How can make a continued fraction in the following format?

Question

How can make a continued fraction in the previous format?

Answer 1

\documentclass{article}
\newcommand\contfrac[2]{\underline{#1}/\overline{#2}}
\begin{document}
\[
\Phi^{n,n}(x) = f_0 + \contfrac{x-x_0}{\phi(x_0,x_1)} +
  \contfrac{x-x_1}{\phi(x_0,x_1,x_2)} + \cdots
\]
\end{document}