Find the number that results in the longest set of terms when using the Collatz sequence

collatz-sequence.py

def collatz_count_until_1(n):
    count = 0
    while n != 1:
        if n % 2 == 0:
            n = n / 2
        else:
            n = (3 * n) + 1
        count += 1
    return count

max = None
for x in range(1, 300000):
    length = collatz_count_until_1(x)
    if max == None or max[0] < length:
        max = (length, x)

print("Maximum stopping distance {0}, starting number {1}".format(max[0], max[1]))