Tikz Fractal - Cantor Dust

Question

Is anyone able to help me draw the following fractal in Tikz?

Here we start of with the unit square, break it into 16 equal squares, and remove 12 of them - leaving 4 arranged as seen. The process is repeated on the remaining squares, and so on.

I am pretty sure I need to use something similar to Nesting fractal tikz decorations but I am not good enough at TeX to compile the code myself.

Thank you in advance.

My code so far:

 \newcommand{\dust}[1]{
     \foreach \i in {1,...,#1}{decorate\{}
     (0,0)--(1,1)
     \foreach \i in {1,...,#1}{\}};

      SOMETHING IN HERE (DON'T KNOW)
 }

 \begin{tikzpicture}
     \path (0,0) pic {dust=5};
 \end{tikzpicture}

Answer 1

It is a nice Lindenmayer system exercise.

\documentclass[border=9,tikz]{standalone}
\usetikzlibrary{lindenmayersystems}
\begin{document}
\pgfdeclarelindenmayersystem{Cantor dust}{
    \symbol{S}{\pgfpathrectangle{\pgfpointorigin}{\pgfpoint{\pgflsystemcurrentstep}{\pgflsystemcurrentstep}}}
    \symbol{U}{\pgftransformyshift{\pgflsystemcurrentstep}}
    \symbol{R}{\pgftransformxshift{\pgflsystemcurrentstep}}
    \rule{S -> [UUSURRS][RSRRUS]}
    \rule{U -> UUUU}
    \rule{R -> RRRR}
}
\tikz;
\tikz\fill[lindenmayer system={Cantor dust,axiom=S,step=320pt,order=1}]lindenmayer system;
\tikz\fill[lindenmayer system={Cantor dust,axiom=S,step= 80pt,order=2}]lindenmayer system;
\tikz\fill[lindenmayer system={Cantor dust,axiom=S,step= 20pt,order=3}]lindenmayer system;
\tikz\fill[lindenmayer system={Cantor dust,axiom=S,step=  5pt,order=4}]lindenmayer system;
\end{document}

Answer 2

I've just discovered this topic, which was related to another, more recent one. It can be considered as an application of recursive programming, for which MetaPost is usually well suited. So here is a MetaPost solution, for whom it may interest.

def cantor_dust(expr x, y, d, n) = 
    if n > 0:
        cantor_dust(x+.25d, y, .25d, n-1);
        cantor_dust(x+.75d, y+.25d, .25d, n-1);
        cantor_dust(x+.5d, y+.75d, .25d, n-1);
        cantor_dust(x, y+.5d, .25d,  n-1);
    else: fill (x, y) -- (x+d, y) -- (x+d, y+d) -- (x, y+d) -- cycle; fi
enddef;
beginfig(1);
    for i = 0 upto 4:
        draw image(cantor_dust(0, 0, 4cm, i)) shifted (4.25cm*i, 0);
    endfor;
endfig;
end.