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edited Jul 23, 2017 at 20:53

Python, 7676 72 bytes

lambdaf=lambda s,k=1:sumlen(k*s)and(2**lenf([*g])-1s,s[0])forif s[0]*abs(k,g in)/k-1else groupbyk+f(ss[1:],2*k))
from itertools import*

lambda s:sum(k*(2**len([*g])-1)for k,g in groupby(s))
from itertools import*

f=lambda s,k=1:len(s)and(f(s,s[0])if s[0]*abs(k)/k-1else k+f(s[1:],2*k))

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created Jul 23, 2017 at 20:20

lambda s:sum(k*(2**len([*g])-1)for k,g in groupby(s))
from itertools import*