The \substack command from the amsmath package can do what you are after:

\documentclass{article}

\usepackage{amsmath}

\begin{document}
\begin{equation*}
  \sum_{\substack{m,n=-\infty,\\(m,n)\neq (0,0)}}^{\infty}\left[\frac{1}{(z-2 m\omega_{1}-2 n\omega_{2})^{2}}-\frac{1}{4(m\omega_{1}+n\omega_{2})^{2}}\right]
\end{equation*}
\end{document}




Or without the comma, since the next condition is on a new line:

\documentclass{article}

\usepackage{amsmath}

\begin{document}
\begin{equation*}
  \sum_{\substack{m,n=-\infty\\(m,n)\neq (0,0)}}^{\infty}\left[\frac{1}{(z-2 m\omega_{1}-2 n\omega_{2})^{2}}-\frac{1}{4(m\omega_{1}+n\omega_{2})^{2}}\right]
\end{equation*}
\end{document}




LaTeX command for double lower index summation
The question title may be misleading, but I have what I think is a common issue for Android newbies: I have an activity with a LinearLayout, and I have an EditText at the bottom of the screen. When I click on it, the keyboard appears over the EditText, hiding it while typing. Is there a way to achieve what most user expect, that is the activity gets scrolled down until the EditText becomes visible again?
