%%
%% The LaTeX Companion, 2ed (second printing August 2004)
%%
%% Example 8-3-3 on page 487.
%%
%% Copyright (C) 2004 Frank Mittelbach, Michel Goossens,
%%    Johannes Braams, David Carlisle, and Chris Rowley
%%
%% 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.
%%

\documentclass{ttctexa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{207.0pt}

\StartShownPreambleCommands
\usepackage{amsmath}
\setcounter{MaxMatrixCols}{20}
\StopShownPreambleCommands
\begin{document}
\[
 \begin{Vmatrix}
  \,a&b&c&d&e&f&g&h&i&j &\cdots\,{} \\
     &a&b&c&d&e&f&g&h&i &\cdots\,{} \\
     & &a&b&c&d&e&f&g&h &\cdots\,{} \\
     & & &a&b&c&d&e&f&g &\cdots\,{} \\
     & & & &\ddots&\ddots&\hdotsfor[2]{5}\,{}
 \end{Vmatrix} \]
\end{document}
