A friend of mine made a program in gamemaker that shows every possible combination in the QR-codes.
there are over 65k combinations possible, so a lot of them won't work, but you're guaranteed to get every one in existence now, and those added in the future.

for the settings, i used 100ms on either random or count up.
You can put 6 windows next to each other in random to get them faster

linky:
http://www.mediafire.com/?5pj9q7o2bide8dc