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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()

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