This was a real challenge, but a good challenge! First, the art, music, and theme were great -- not distracting at all while my brain is wrapped in a knot trying to figure the equation out. I made it about 8 or 10 levels deep (but I need to go to sleep now haha). Some I could figure out pretty quickly but others were really tough, it's hard to think in a circle :)
I think if there are a finite number of levels it would be helpful to have a level number or progress bar to be able to see how far you've gone. Great design!