There are a few "special" ones in English.
R^2 = "R squared" or "R to the second"
R^3 = "R cubed" or "R to the third"
Two and three are the only ones that I know of that have a "special" word like squared and cubed. Anything else is like this:
R^4 = "R to the fourth"
R^5 = "R to the fifth"
I speak U.S. English, for whatever that's worth. The Brits and Aussies and all of those guys probably use something different :-D