foo.py

a = bin(999999999)[2:]
temp = []
for i, v in enumerate(a):
    if v == '1':
        temp.append(len(a) - i)
print a
print temp

# 111011100110101100100111111111
# [30, 29, 28, 26, 25, 24, 21, 20, 18, 16, 15, 12, 9, 8, 7, 6, 5, 4, 3, 2, 1]