Given an=2an−1+1a_n = 2a_{n-1} + 1an=2an−1+1 and a0=1a_0 = 1a0=1. What is the closed-form expression for ana_nan?
an=2na_n = 2^nan=2n
an=2n+1−1a_n = 2^{n+1} - 1an=2n+1−1
an=2n+1+1a_n = 2^{n+1} + 1an=2n+1+1
an=3⋅2n−1a_n = 3 \cdot 2^n - 1an=3⋅2n−1