\documentclass[border=10pt]{standalone}
\usepackage{pgf,tikz}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}

\begin{document}
\begin{tikzpicture}[scale=1]
\foreach \a in {9}
\foreach \b in {-1,...,-\a}
\foreach \x in {\b}
\foreach \y in {-1,...,\b}{
\draw[fill=blue] (\x,\y) circle (2mm);
\draw[fill=red] (\y,\x-1) circle (2mm);
\draw[tchick] (\b-.5,\b-1) -- (-.5,-1);
}

\end{tikzpicture}

\end{document}