This is a concept I've never understood on a solid mathematical level.

Say you've got 33 on a 37A rainbow board, and you're confident that the nitty-ass villain you're up against is holding either AK or AA.

Now (assuming your read is 100% accurate), if it was equally likely that villain is holding AK as he is to be holding AA, then felting this would be basically 0EV, since you're a huge dog vs half his range and a huge favorite vs the other half.

But there are more combinations of AK than there are AA, so he's more likely to be holding AK then he is AA, so felting this becomes +EV.

...am I on the right track here? How many more combinations of AK are there than paired hands?

The implications of this then are that you have to weigh the likelihood of unpaired cards in villain's range higher than you do paired cards, right? but how much more?