'''Sylvester's sequence'''

from functools import reduce
from itertools import count, islice


# sylvester :: [Int]
def sylvester():
    '''Non-finite stream of the terms
       of Sylvester's sequence.
       (OEIS A000058)
    '''
    def go(n):
        return 1 + reduce(
            lambda a, x: a * go(x),
            range(0, n),
            1
        ) if 0 != n else 2

    return map(go, count(0))


# ------------------------- TEST -------------------------
# main :: IO ()
def main():
    '''First terms, and sum of reciprocals.'''

    print("First 10 terms of OEIS A000058:")
    xs = list(islice(sylvester(), 10))
    print('\n'.join([
        str(x) for x in xs
    ]))

    print("\nSum of the reciprocals of the first 10 terms:")
    print(
        reduce(lambda a, x: a + 1 / x, xs, 0)
    )


# MAIN ---
if __name__ == '__main__':
    main()