A lower bound for A350155 can be optained with the pattern below.
A350155(n) >= 3 * 2^n - 6

Mirrors are shown as '\' or '/', empty locations are '.', and the starting location of the laser is 'V'.
Found by Benjmain Butin. 20th January 2022.

Example for a grid of size 10, 3066 its.

V
\\......\\
.\\....\\.
..\\..\\..
...\\\\...
....\\....
...\\//...
..\\..//..
.\\....//.
\\......//
\......../

Example for a grid of size 11, 6138 hits.

V
\\.......\\
.\\.....\\.
..\\...\\..
...\\.\\...
....\\\....
....\\/....
...\\.//...
..\\...//..
.\\.....//.
\\.......//
\........./