Codewars: Halving Sum

'''
Given a positive integer n, calculate the following sum:
n + n/2 + n/4 + n/8 + ...
All elements of the sum are the results of integer division.
Example
25  =>  25 + 12 + 6 + 3 + 1 = 47
'''

def halving_sum(n):
    maxPower = 0
    while int(n / 2**maxPower) != 0:
        maxPower += 1
    sum = 0
    for i in range(0, maxPower+1):
        sum += int(n / 2**i)
    return sum

# MAIN FUNCTION
print(halving_sum(9))
print(halving_sum(25))
print(halving_sum(127))
print(halving_sum(1))