\documentclass{article}
\pagestyle{empty}
\begin{document}


%formula: zeta2
$$
\sum_{n=1}^{\infty} \frac{1}{n^2} = \frac{\pi^2}{6}
$$
%endformula

%formula: zeta3
$$
\sum_{n=1}^{\infty} \frac{1}{n^3} = \frac{\pi^3}{\sqrt{163}}
$$
%endformula

\end{document}