Given an=3an−1+2n+1a_n = 3a_{n-1} + 2^{n+1}an=3an−1+2n+1, what is the form of the particular solution?
A⋅2nA \cdot 2^nA⋅2n
A⋅3nA \cdot 3^nA⋅3n
A⋅n⋅2nA \cdot n \cdot 2^nA⋅n⋅2n
A⋅n⋅3nA \cdot n \cdot 3^nA⋅n⋅3n