Nice!
I've completed the ultra challenge by just applying the same algorithm i used in base four. Although I probably misunderstood the trivia question
It was my mistake. Currently, the trivia question's actual answer is infinite, of course.
The infinite algorithm was unintended, resulting from the difference in uniqueness rules between this game and the Weak Tree Function. I'm hoping to patch it out later today. [edit: Finally fixed it, about a week later.]