1def collatz(a: int) -> int:
 2    return a // 2 if a % 2 == 0 else 3 * a + 1
 3
 4def collatz_sequence(a: int) -> int:
 5    result: str = ""
 6    result += f"{a}: "
 7    i: int = a
 8    while i >= 1:
 9        if i == 1:
10            result += "1"
11            break
12        result += f"{i}, "
13        i = collatz(i)
14    return result
15
16def main():
17    print("\n".join([collatz_sequence(i) for i in range(1, 10001)]))