#!/usr/bin/env python

import sys

def collatz(number):
# Executes collatz sequence until number = 1
    if int(number) % 2 == 0:
        print(str(number)+ ' // 2 =')
        return int(number) // 2
    else:
        print(str(number) + ' * 3 + 1 =')
        return int(number) * 3 + 1

# Main program
try:
    number = int(input('\nEnter number: '))
except ValueError:
    print('i need a pos int')
    sys.exit()

original = int(number) + 0

counter = 0
print
while True:
    if number == 1:
        break
    else:
        number = collatz(number)
        counter += 1
print('\nThe collatz sequence was completed on the number ' + str(original) +
    ' in ' + str(counter) + ' steps.\n')