Clojure's data structures are implemented using trees that have a 32-way branching factor, so each node has 32 children, instead of the 2 you'd see in a binary search tree. A lot of things you might expect to be O(1), like checking for membership in a set, or getting the nth element of a vector, actually take O(log_base_32(n)).

Ah, I see. That doesn't matter in big-O notation, though, because log_32(n) = log_2(n) / log_2(32), that is the difference between two bases is a constant factor.

I was a bit confused because O(log_32(n)) = O(log(n)) = log(32)+log(n) = O(log(32n)), so no matter how I parsed it I would just get O(log(n)) :)