Find the Sum of the Finite Geometric Sequence $\sum _ { n = 1 } ^ { 7 } 2 ^ { n - 1 }$

Find the sum of the finite geometric sequence. $\sum _ { n = 1 } ^ { 7 } 2 ^ { n - 1 }$

A) 43
B) 22
C) 127
D) 63
E) 31