What is the generating function A(x)A(x)A(x) for the sequence an=3na_n = 3^nan=3n?
A(x)=11−3xA(x) = \frac{1}{1-3x}A(x)=1−3x1
A(x)=11+3xA(x) = \frac{1}{1+3x}A(x)=1+3x1
A(x)=3x1−xA(x) = \frac{3x}{1-x}A(x)=1−x3x
A(x)=13−xA(x) = \frac{1}{3-x}A(x)=3−x1