\begin{figure}[h!]
  \centering
  \begin{tikzpicture}[scale=2]
    % Radii of inner (central) and outer (duplex) hexagons
    \def\r{1.0}
    \def\R{1.6}

    % Inner hexagon vertices (central pi-matrix)
    \foreach \i/\p in {0/2,1/3,2/5,3/7,4/11,5/13}{
      \node (c\i) at ({\r*cos(60*\i)},{\r*sin(60*\i)}) {$p_{\p}$};
    }

    % Outer hexagon vertices (duplex layer)
    \foreach \i/\p in {0/17,1/19,2/23,3/29,4/31,5/37}{
      \node (d\i) at ({\R*cos(60*\i)},{\R*sin(60*\i)}) {$p_{\p}$};
    }

    % Inner hexagon edges
    \foreach \i in {0,...,5}{
      \pgfmathtruncatemacro{\j}{mod(\i+1,6)}
      \draw (c\i) -- (c\j);
    }

    % Outer hexagon edges
    \foreach \i in {0,...,5}{
      \pgfmathtruncatemacro{\j}{mod(\i+1,6)}
      \draw (d\i) -- (d\j);
    }

    % Duplex links between inner and outer vertices
    \foreach \i in {0,...,5}{
      \draw[dashed] (c\i) -- (d\i);
    }
  \end{tikzpicture}
  \caption{Allenium duplex chamber: central $\pi$-matrix hexagon and duplex
           layer filled by the first twelve primes.}
\end{figure}