Collatz conjecture

collatz.py

#!/usr/bin/env python

from __future__ import division
import matplotlib.pyplot as plt

print('Enter integer number')
number = int(input())

collatz_series = []
collatz_series.append(number)

if number == 1:
    number = number * 3 + 1
    collatz_series.append(number)

while number != 1:
    if number % 2 == 0:
        number = number / 2
        collatz_series.append(number)
    else:
        number = number * 3 + 1
        collatz_series.append(number)
    if number == 1:
        break

print('Collatz series:')
print(collatz_series)


x = []

for e,i in enumerate(collatz_series):
    x.append((e+1)/len(collatz_series))

plt.plot(x,collatz_series)
plt.xlabel('Normalized number in sequence')
plt.ylabel('Collatz value')
plt.show()