Count up in a somewhat complex way

Ah, the factorial number system! Used to map a single number n to a single permutation of an array. Been used quite much, actually. It's a good tool.

321

Code:

def toFNS(n):
    k = 0
    while fact(k) <= n:
        k += 1
    indexList = []
    numberList = range(k).reversed()
    for x in numberList:
        quot = n // fact(x)
        indexList.append(quot)
        n %= fact(x)
    return indexList

Noah