In [1]:

    

import collections


    

In [2]:

    

def prime_factorize(n):
    a = []
    while n % 2 == 0:
        a.append(2)
        n //= 2
    f = 3
    while f * f <= n:
        if n % f == 0:
            a.append(f)
            n //= f
        else:
            f += 2
    if n != 1:
        a.append(n)
    return a


    

In [3]:

    

print(prime_factorize(1))


    

    




[]

In [4]:

    

print(prime_factorize(36))


    

    




[2, 2, 3, 3]

In [5]:

    

print(prime_factorize(840))


    

    




[2, 2, 2, 3, 5, 7]

In [6]:

    

c = collections.Counter(prime_factorize(840))
print(c)


    

    




Counter({2: 3, 3: 1, 5: 1, 7: 1})

In [7]:

    

print(c.keys())


    

    




dict_keys([2, 3, 5, 7])

In [8]:

    

print(c.values())


    

    




dict_values([3, 1, 1, 1])

In [9]:

    

print(c.items())


    

    




dict_items([(2, 3), (3, 1), (5, 1), (7, 1)])

In [10]:

    

print(list(c.keys()))


    

    




[2, 3, 5, 7]