Assume the Carmichael's Totient Function Conjecture.

How fast does this chain grow?

$$n_0=\phi(3^2)\rightarrow n_1=\phi((\phi^{-1}(n_0))^2)\rightarrow n_2=\phi((\phi^{-1}(n_1))^2)\rightarrow\dots$$

where $\phi^{-1}(\phi(x))$ is the smallest second integer $y\neq x$ such that $\phi(x)=\phi(y)$.

Does growth remain similar if $3^2$ is replaced by $a^k$ where $a,k\geq3$?