Or the inverse TREE() function [1]. There's also the inverse Busy Beaver function if you don't insist on computability... [1] https://en.wikipedia.org/wiki/Kru

Or the inverse TREE() function [1]. There's also the inverse Busy Beaver function if you don't insist on computability... [1] https://en.wikipedia.org/wiki/Kruskal%27s_tree_theorem#TREE(3) https://en.wikipedia.org/wiki/Kruskal%27s_tree_theorem#TREE(...