What is the sum of the geometric series in which a1 = 4, r = 2, and an = 512? Hint: cap s sub n equals start fraction a sub one left parenthesis one minus r to the power of n end power right parenthesis over one minus r end fraction comma r ≠ 1, where a1 is the first term and r is the common ratio.

Sn = 1,020
Sn = −252
Sn = 43,690
Sn = −1,020