Anonymous user asked a question on Quora that, How and Why Google is showing porn results in when one type equation -4^(1/4) into Google search query ? This is really a very strange bug on Google.
Amazed that Google doesn’t address this yet. Apparently they are trying to fix it…
May be a forgotten Easter Egg or prank from developers? 
maybe thats a hidden stash of some employees
Interesting . :azn:
I just tried it and according to Google Search I got about 127 results. When I tried displaying the omitted results no results came up. I’m wondering if that’s a separate bug or part of the other one.