Are you sure that formula is right? f(x)=x^g is a strictly monotonic function for all positive g, so the ordering of the scores will stay the same no matter what constant is used for g (assuming g is positive).
It's a bit more involved than that. There are factors like nonURL posts etc. It's been some time since ycombinator.com/arc held the source code of HN (it no longer holds the source code) so I can not verify the actual formula.