Set partitions of a 4-set notated using modifications of traditional Japanese Genji chapter or Genji-Kô symbols.  In the visual conventions of these symbols, elements which are under a common horizontal bar are grouped together -- except that where a vertical stem crosses a horizontal bar (as opposed to a corner or "T"), this does not indicate a grouping.  Therefore the middle green symbol in the second row indicates a grouping of elements 1 and 3 together, and a separate grouping of 2 and 4 together.  There are 15 symbols because 15 is a Bell number.  When the original SVG file is viewed in appropriate software, the modern notation of the set partition is shown in the orange-bordered white box at lower right if a pointing device (mouse) is placed over a symbol. The plot illustrates an algorithm to generate the partitions.
Own work
Peter Luschny