In a geometric sequence a1=1,an=1/2n−1a_1=1, a_n=1/2^{n-1}a1=1,an=1/2n−1, what is the product of the first nnn terms?
2−n(n−1)/22^{-n(n-1)/2}2−n(n−1)/2
2−n2^{-n}2−n
2−(n+1)/22^{-(n+1)/2}2−(n+1)/2
2n22^{n^2}2n2