%% 
%%  Example 02-11-1 
%%  Copyright (C) 2016 Herbert Voss
%% 
%% ==== 
% Show page(s) 1
%% 
%% 
\documentclass[]{screxa}
\pagestyle{empty}
\setlength\textwidth{158.31393pt}
\setlength\parindent{0pt}
\usepackage[T1]{fontenc}
\usepackage{kpfonts}
%StartShownPreambleCommands
\usepackage{amsmath}
%StopShownPreambleCommands
\begin{document}
\begin{equation}
  \sum_{%
    \substack{1\le i\le p\\
              1\le j\le q\\
              1\le k\le r}
  }a_{ij}b_{jk}c_{ki}
\end{equation}
\end{document}
