Generate smooth numbers

smooth.py

import itertools


def times(n, g):
    for i in g:
        yield n * i


def merge(g, h):
    ng = next(g)
    nh = next(h)
    while 1:
        if ng < nh:
            yield ng
            ng = next(g)
        elif ng > nh:
            yield nh
            nh = next(h)
        else:
            yield ng
            ng = next(g)
            nh = next(h)


def smooth_numbers(primes=(2, 3, 5)):
    def _f():
        yield 1
        mm = times(primes[0], mp[0])
        for p, g in zip(primes[1:], mp[1:]):
            mm = merge(mm, times(p, g))
        yield from mm

    m = _f()
    *mp, res = itertools.tee(m, len(primes) + 1)
    return res


# Generates all 5-smooth numbers in order
# For k-smooth numbers use: tuple(sympy.primerange(1, k+1))
primes = (2, 3, 5)  

for n in smooth_numbers(primes):
    print(n)