The functions $a_n^{(1)} = 3^n$ and $a_n^{(2)} = n \cdot 3^n$ are solutions to a second-order homogeneous linear recurrence. Compute their Casoratian (discrete Wronskian):

$W_n = a_n^{(1)} a_{n+1}^{(2)} - a_n^{(2)} a_{n+1}^{(1)}$

Which statement is true?