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def collatz_sequence(n):
"""
Collatz conjecture: start with any positive integer n.Next term is obtained from the previous term as follows:
if the previous term is even, the next term is one half of the previous term.
If the previous term is odd, the next term is 3 times the previous term plus 1.
The conjecture states the sequence will always reach 1 regaardless of starting value n.
Example:
>>> collatz_sequence(43)
[43, 130, 65, 196, 98, 49, 148, 74, 37, 112, 56, 28, 14, 7, 22, 11, 34, 17, 52, 26, 13, 40, 20, 10, 5, 16, 8, 4, 2, 1]
"""
sequence = [n]
while n != 1:
if n % 2 == 0: # even number condition
n //= 2
else:
n = 3 * n + 1
sequence.append(n)
return sequence
def main():
n = 43
sequence = collatz_sequence(n)
print(sequence)
print("collatz sequence from %d took %d steps." % (n, len(sequence)))
if __name__ == "__main__":
main()