%% 
%%  Der Mathematiksatz mit LaTeX, 1. Auflage 2009
%% 
%%  Example 10-10-3 on page 237.
%% 
%%  Copyright (C) 2009 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.
%% 

\documentclass[]{ttctexa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{170.59192pt}
\AtBeginDocument{\setlength\parindent{0pt}}
\StartShownPreambleCommands
\usepackage{amsmath}
\def\pM{\ensuremath{%
  \genfrac{}{}{0pt}{}{+}%
    {\scriptstyle(\kern-1pt-\kern-1pt)}}}
\StopShownPreambleCommands
\begin{document}
{\Large$\pM$}\\   $y=\pM\cdots$
\end{document}