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44 lines
1.0 KiB
Python
44 lines
1.0 KiB
Python
"""
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Calculates the nth number in Sylvester's sequence
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Source:
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https://en.wikipedia.org/wiki/Sylvester%27s_sequence
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"""
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def sylvester(number: int) -> int:
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"""
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:param number: nth number to calculate in the sequence
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:return: the nth number in Sylvester's sequence
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>>> sylvester(8)
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113423713055421844361000443
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>>> sylvester(-1)
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Traceback (most recent call last):
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...
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ValueError: The input value of [n=-1] has to be > 0
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>>> sylvester(8.0)
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Traceback (most recent call last):
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...
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AssertionError: The input value of [n=8.0] is not an integer
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"""
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assert isinstance(number, int), f"The input value of [n={number}] is not an integer"
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if number == 1:
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return 2
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elif number < 1:
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raise ValueError(f"The input value of [n={number}] has to be > 0")
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else:
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num = sylvester(number - 1)
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lower = num - 1
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upper = num
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return lower * upper + 1
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if __name__ == "__main__":
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print(f"The 8th number in Sylvester's sequence: {sylvester(8)}")
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