Revision history [back]

This is a LaTeX issue. The array environment must be inside a math environment. Try the following:

\[ 
\begin{array}{|l|cccccccc}
  & 1 & 2 & 3 & 4 & 5 & .. & r\\
\hline
1 & 1/1 & 2/1 & 3/1 & 4/1 & 5/1 & ..& r/1\\
2 & 1/2 & {2/2} & 3/2 & 4/2 & 5/2 & ..& r/2\\
3 & 1/3 & 2/3 & 3/3 & 4/3 & 5/3 & ..& r/3\\
4 & 1/4 & 2/4 & 3/4 & 4/4 & 5/4 & ..& r/4\\
5 & 1/5 & 2/5 & 3/5 & 4/5 & 5/5 & ..& r/5\\
..&  .. & ..  & ..  &  .. & ..  & ..& .. \\
r &  1/r & 2/r & 3/r  & 4/r & 5/r  & .. & r/r\\
\end{array}
\]

Also, you had a \st command in one line that was not defined.