What value does 1+2+4+8+⋯+2n−11 + 2 + 4 + 8 + \cdots + 2^{n-1}1+2+4+8+⋯+2n−1 equal?
2n−12^n - 12n−1
2n2^n2n
2n+12^n + 12n+1
n⋅2n−1n \cdot 2^{n-1}n⋅2n−1