
Update It's possible to calculate the position of the nodes directly with \n
with
\foreach \n in {1,...,4}{%
\node [draw,circle,ultra thick,red,num,
minimum width=1.5 cm,fill=white] at
({2+4*mod(\n+1,2)},{2+(3-\n)*(4-\n)*(4*\n-2)/3}) {\n};
I didn't try to find something perhaps more simpler.
\documentclass[11pt]{scrartcl}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[num/.style={font=\Huge\bfseries\ttfamily}]
\draw[ultra thick,red] (0,0) rectangle (8,8)
(4,0) -- (4,8)
(0,4) -- (8,4);
\draw [gray,thick] (2,0) -- (2,8)
(6,0) -- (6,8)
(0,2) -- (8,2)
(0,6) -- (8,6);
\foreach \n/\x/\y in {1/2/6,2/6/6,3/2/2,4/6/2}{%
\node [draw,circle,ultra thick,red,num,
minimum width=1.5 cm,fill=white] at (\x,\y) { \n};
\node[num] at (\n*2-1,8.5) {\n};
\node[num] at (-0.5,9-\n*2) {\n};
}
\node[num] at (-0.5,8){R};
\node[num] at (0.5,8.5){S} ;
\end{tikzpicture}
\end{document}
Another possibility like N3buchadnezzar wrote in a comment is to use grid, the code is reduced and with the update the code is only this :
\documentclass[11pt]{scrartcl}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[num/.style={font=\Huge\bfseries\ttfamily}]
\draw [gray,thick,step=2cm] (0,0) grid (8,8);
\draw[ultra thick,red,step=4cm] (0,0) grid (8,8);
\foreach \n in {1,...,4}{%
\node [draw,circle,ultra thick,red,num,
minimum width=1.5 cm,fill=white] at
({2+4*mod(\n+1,2)},{2+(3-\n)*(4-\n)*(4*\n-2)/3}) { \n};
\node[num] at (\n*2-1,8.5) {\n};
\node[num] at (-0.5,9-\n*2) {\n};}
\node[num] at (-0.5,8){R};
\node[num] at (0.5,8.5){S} ;
\end{tikzpicture}
\end{document}