Tried my hand at doing this with US states, feel free to contribute any improvements
https://docs.google.com/spreadsheets/d/1QUdlGrjWuo77QFAjBd1p...
1 karma · joined December 20, 2013
https://docs.google.com/spreadsheets/d/1QUdlGrjWuo77QFAjBd1p...
^(x|(xx){1,9}|x{32}|(x{64})+)$