Answer
geometric,
$r= 8$
$S_n= \frac{8(8^n-1)}{7}$
Work Step by Step
1. Based on the given sequence, we can determine it is geometric,
2. We can find the common ratio as $r=\frac{s_2}{s_1}=\frac{2^6}{2^3}=2^3=8$
3. We can find the sum of the first n terms as $S_n=\frac{s_1(r^n-1)}{r-1}=\frac{2^3(8^n-1)}{8-1}=\frac{8(8^n-1)}{7}$
