%% 
%%  Ein Beispiel der DANTE-Edition
%%  Mathematiksatz mit LaTeX
%%  3. Auflage
%%  Beispiel 04-18-6 auf Seite 71.
%%  Copyright (C) 2018 Herbert Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%%  See http://www.latex-project.org/lppl.txt for details.
%% 
%% ==== 
% Show page(s) 1
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\documentclass[10pt]{screxa}
\pagestyle{empty}
\setlength\textwidth{122.40707pt}
\AtBeginDocument{\setlength\parindent{0pt}}
%StartShownPreambleCommands

%StopShownPreambleCommands
\begin{document}
\[ \sum_{%
  \makebox[0pt]{${{\scriptscriptstyle 1\le j\le p\atop {%
      {1\le j\le q\atop 1\le k\le r}}}}%
    $}}a_{ij}\mathbf{b_{jk}}c_{ki}
\]
\end{document}