Well, I did the math.

Theory: Hz correlates to pitch by it's relation in the overtone series, where a doubling of Hz yields an octave in pitch, and a tripling of Hz yields and octave and a fifth.

If you assume C=256, you can cycle through to discover G=384, D=576, and A=867.

We can also say that half of your initial Hz is equivalent to an octave down in pitch.

Therefore, A is harmonically 433.5, when C=256.

That last article is really interesting. I'm a firm believer in math, and I know that pianos are tuned incorrectly in order to make them chromatic instruments, so 432/433.5 is probably a better tuning for A.