Task
Produce an ASCII representation of a Sierpinski triangle of order   N.



Example
The Sierpinski triangle of order   4   should look like this:

                       *
                      * *
                     *   *
                    * * * *
                   *       *
                  * *     * *
                 *   *   *   *
                * * * * * * * *
               *               *
              * *             * *
             *   *           *   *
            * * * *         * * * *
           *       *       *       *
          * *     * *     * *     * *
         *   *   *   *   *   *   *   *
        * * * * * * * * * * * * * * * *



Related tasks
 Sierpinski triangle/Graphical for graphics images of this pattern. 
 Sierpinski carpet


%!PS-Adobe-3.0
%%BoundingBox 0 0 300 300
 
/F { 1 0 rlineto } def
/+ { 120 rotate } def
/- {-120 rotate } def
/v {.5 .5 scale } def
/^ { 2  2 scale } def
/!0{ dup 1 sub dup -1 eq not } def
 
/X { !0 { v X + F - X - F + X ^ } { F } ifelse pop } def
 
0 1 8 { 300 300 scale 0 1 12 div moveto
        X + F + F fill showpage         } for
%%EOF