Answer:
384 but see below.
Step-by-step explanation:
Remark
A_n = 3*2^(n - 1) I will assume that's what you mean. I'll give the answer for A_n = 3*2^n - 1 as well.
Solution
n = 8
A_n = 3 *2^(8 - 1)
A_8 = 3*2^7
A_8 = 3* 128
A_8 = 384
If you mean A_n = 3*2^n - 1
Then you would get
A_n =3 * 2^8 - 1
A_8 = 3 * 256 - 1
A_8 = 768 - 1
A_8 = 767
