$\log^k(n) = \log(\log(\log(...\log(n))));$ Let $f(n)$ = smallest $k$, s.t. $\log^k(n) \leq 1$ Is there known name for function $f$ ? Or it's an instance of some known function ? Basically I want to know if anyone else also treating $O(f(n))$ as good as $O(1)$. Login To add answer/comment