iframe-proxy | Sunbelt Computer Software

44 lines (33 loc) · 1.05 KB

"""

Calculates the nth number in Sylvester's sequence

Source:

https://en.wikipedia.org/wiki/Sylvester%27s_sequence

"""

def sylvester(number: int) -> int:

"""

:param number: nth number to calculate in the sequence

:return: the nth number in Sylvester's sequence

>>> sylvester(8)

113423713055421844361000443

>>> sylvester(-1)

Traceback (most recent call last):

...

ValueError: The input value of [n=-1] has to be > 0

>>> sylvester(8.0)

Traceback (most recent call last):

...

AssertionError: The input value of [n=8.0] is not an integer

"""

assert isinstance(number, int), f"The input value of [n={number}] is not an integer"

if number == 1:

return 2

elif number < 1:

msg = f"The input value of [n={number}] has to be > 0"

raise ValueError(msg)

else:

num = sylvester(number - 1)

lower = num - 1

upper = num

return lower * upper + 1

if __name__ == "__main__":

print(f"The 8th number in Sylvester's sequence: {sylvester(8)}")

Sunbelt Computer Software