Question

first five terms in the geometric sequence an =(2)^n-1 starting with n^1

Answer 1

I'm assuming you meant "starting with n=1". If so, just start substituting in values for n:

a1 = 2^(1-1) = 2^0 = 1
a2 = 2^(2-1) = 2^1 = 2
and so on.