This problem involves geometric progression..
Remember that the summation of terms in a geometric progression is defined by the formula,  S_{n} =  a_{1}  \frac{1-r^n}{1-r}
where Sn is the total number, a1 is the first term, r is the common ratio or the multiplier to have the next term and n is the number of terms.
Knowing that the first term is 1, r is 2 and n is 6 then you'll have it as:
 S_{n} = 1( \frac{1 - 2^6}{1 - 2} )
 S_{n} = 63