here is my LaTeX: (how does one format it nicely?): [Edit:] Reducing the example
\documentclass{article}
\usepackage{longtable}
\usepackage{lscape}
\begin{document}
\begin{landscape}
\noindent
\begin{longtable}{ll}
\caption[]{Decomposition } \\
& \\ \endhead\hline
&
$ \begin{array}{l}
1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\ +1 \\
\end{array}$
\end{longtable}
\end{landscape}
\end{document}
And here is what I get: latest reduced example
Thanks for your help in advance!