How to make number triangles

I wish to do in LaTeX what I did in mathjax here in a very lousy way:

$$A$$
$$B \qquad B$$
$$R \qquad R \qquad R$$
$$A\qquad A \qquad A \qquad A$$
$$C\qquad C\qquad C\qquad C\qquad C$$
$$A\qquad A \qquad A \qquad A \qquad A\qquad A$$
$$D\qquad D\qquad D\qquad D\qquad D$$
$$A\qquad A \qquad A \qquad A$$
$$B \qquad B \qquad B$$
$$R \qquad R$$
$$A$$


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One option would be to use the gather* environment from amsmath:

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{gather*}
A \\
A
\end{gather*}

\begin{gather*}
A \\
A
\end{gather*}

\end{document}


EDIT: a simple TikZ approach:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{matrix}

\begin{document}

\begin{tikzpicture}
\matrix[matrix of math nodes,column sep=0pt,inner sep=0pt,row sep=10pt]
{
&&&&& A \\
&&&& B && B \\
&&& R && R && R \\
&& A && A && A && A \\
& C && C && C && C && C \\
A && A && A && A && A && A \\
& D && D && D && D && D \\
&& A && A && A && A \\
&&& B && B && B \\
&&&& R && R \\
&&&&& A \\
};
\end{tikzpicture}

\end{document}


EDIT2: a more "pintoresque" design using TikZ:

\documentclass{article}
\usepackage{tikz}

\begin{document}
\centering

\begin{tikzpicture}[x=13mm,y=9mm]
\tikzset{every node/.style={
minimum height=5mm,
inner sep=.7mm,
text width=10mm,
align=center,
font=\small\bfseries\sffamily,
text=olive!50!black,
draw=olive,
top color=olive!5,
bottom color=olive!40,
rounded corners=2.3mm,
}
\foreach \row/\letterT/\letterB in {0/A/A,1/B/R,2/R/B,3/A/A,4/C/D,5/A} {
\foreach \col in {0,...,\row} {
\coordinate (pos) at (-\row/2+\col,-\row);
\node at (pos) {\letterT};
\coordinate (posB) at (-\row/2+\col,\row-10); % use: \row-2 times the max. value for \row
\node at (posB) {\letterB};
}
}
\end{tikzpicture}

\end{document}


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@doncherry: thank you for re-uploading the images! – Gonzalo Medina Sep 8 '11 at 0:00
You're very welcome. I'm always curious what the solutions look like so it's really just to satisfy my nosiness :) – doncherry Sep 8 '11 at 0:02

Put it into a center environment without math

\documentclass{article}
\begin{document}
\begin{center}
A\\
B B\\
R R R\\
A A A A\\
C C C C C\\
A A A A A A\\
D D D D D\\
A A A A\\
B B B\\
R R\\
A
\end{center}

\begin{center}\fontdimen2\font=12pt
A\\
B B\\
R R R\\
A A A A\\
C C C C C\\
A A A A A A\\
D D D D D\\
A A A A\\
B B B\\
R R\\
A
\end{center}

\end{document}


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