Tupper's formula is an inequality defined by Jeff Tupper as . It is know as the "self-referential" formula because if you plug in a certain y value, it plots a pixelated version of itself. This happens because it plots every possible 106 x 17 combination of pixels. If you could zoom out, you could see every 17 pixel tall bitmap stacked on top of each other. You can read more about it on wikipedia.