Crivo de Eratóstenes, Função Totiente de Euler

phi.py

from __future__ import division
def phi(i):
    l=[]
    n=1
    multiples = set()
    for p in range(2, i+1):
        if p not in multiples:
            multiples.update(range(p*p, i+1, p))
            if i%p==0:
                j=(p-1)/p
                l.append(j)
    for j in l:
        n*=j
    n=i*n
    print n
           
phi(420)