http://en.wikipedia.org/wiki/Non-standard_positional_numeral_systems http://en.wikipedia.org/wiki/Non-standard_positional_numeral... http://en.wikipedia.org/wi

http://en.wikipedia.org/wiki/Non-standard_positional_numeral_systems http://en.wikipedia.org/wiki/Non-standard_positional_numeral... http://en.wikipedia.org/wiki/Factorial_number_system http://en.wikipedia.org/wiki/Factorial_number_system (which makes your indexing as simple as reading the digits from the number, i think) yes - here it is - http://en.wikipedia.org/wiki/Factorial_number_system#Permutations http://en.wikipedia.org/wiki/Factorial_number_system#Permuta... :o)