I am also stuck on the number of episodes.
I think season 1 should have 10 or 8 episodes because it is 8 or more episodes and it must be divisible by 2.
Season 2 has 9 episodes, stated outright.
Season 3 would either have 4 or 5 episodes as it is half of season 1.
Season 5 is the last season and has the same number of episodes as season 1.
Season 4 would then have the leftover episodes required to make 39 which would be either 10 or 5.
I have tried the two possible variations but they wont work.
Which piece of logic am I misunderstanding?