collatz conjecture

conjecture: for every positive integer n, the loop terminates, and the last number printed is 1

xkcd wiki

odd pix: 25 99 199 299 399 499 599 699 799 899 999

def collatz(n):
    while n > 1:
        print n
        if n % 2 == 0:
            n = n / 2
        else:
            n = n * 3 + 1
    print n