Constant Digit Scanning

# python3 '/path/to/Constant_Digit_Scanning.py'

data = ''

with open('/path/to/constant.txt') as the_file: data = the_file.read()

for n in range(1, 15):
    tried = set()

    for i in range(0, len(data)):
        num = data[i:i + n]

        if len(num) != n: exit()        # Program has run to the end of the constant

        if num not in tried:
            tried.add(num)

        if len(tried) == 10 ** n:
            print(num)
            break