Taken from http://news.yahoo.com/s/livescience/2009
13 facts about Friday the 13th.
"13. The seals on the back of a dollar bill include 13 steps on the pyramid, 13 stars above the eagle's head, 13 war arrows in the eagle's claw and 13 leaves on the olive branch. So far there's been no evidence tying these long-ago design decisions to the present economic situation. "