Practical numbers in Lucas sequences

A \emph{practical number} is a positive integer $n$ such that all the positive integers $m \leq n$ can be written as a sum of distinct divisors of $n$. Let $(u_n)_{n \geq 0}$ be the Lucas sequence satisfying $u_0 = 0$, $u_1 = 1$, and $u_{n + 2} = a u_{n + 1} + b u_n$ for all integers $n \geq 0$, where $a$ and $b$ are fixed nonzero integers. Assume $a(b + 1)$ even and $a^2 + 4b > 0$. Also, let $\mathcal{A}$ be the set of all positive integers $n$ such that $|u_n|$ is a practical number. Melfi proved that $\mathcal{A}$ is infinite. We improve this result by showing that $\#\mathcal{A}(x) \gg x / \log x$ for all $x \geq 2$, where the implied constant depends on $a$ and $b$. We also pose some open questions regarding $\mathcal{A}$.