find all multiplicands and multipliers for a number

[Paul Rubin]

Steven D'Aprano <steve+comp.lang.python at pearwood.info> writes:
> http://code.activestate.com/recipes/577821-integer-square-root-function/

The methods there are more "mathematical" but probably slower than what
I posted.

Just for laughs, this prints the first 20 primes using Python 3's 
"yield from":

    import itertools

    def sieve(ps):
        p = ps.__next__()
        yield p
        yield from sieve(a for a in ps if a % p != 0)

    primes = sieve(itertools.count(2))
    print(list(itertools.islice(primes,20)))

It's not that practical above a few hundred primes, probably.