Fourier

# This is not built in to python!
# https://stackoverflow.com/a/28825390/33264
def digit_to_char(digit):
    if digit < 10:
        return str(digit)
    return chr(ord('a') + digit - 10)

def str_base(number, base):
    while number > 0:
        number, digit = divmod(number, base)
        yield digit_to_char(digit)

candidates = {}
target = 9999
inital_fours = len([x for x in str(target) if x =="4"])
for base in range(2,24):
    candidate = "".join([x for x in str_base(target, base)])
    fouriness = len([x for x in candidate if x =="4"])
    if fouriness>0:
        candidates[(candidate, base)] = fouriness

max_fours = max(candidates.values())

for candidate, fours in candidates.items():
    if fours == max_fours:
        print("{0} (base {1}) is fouriest".format(candidate[0], candidate[1]))
    if fours > inital_fours:
        print("{0} (base {1}) is fourier".format(candidate[0], candidate[1]))