7 is the only real selection D for which the equation 2n − D = x2 has a lot more than two answers for n and x pure. In particular, the equation 2n − 7 = x2 is recognized as the Ramanujan–Nagell equation. Polynices was one of the 7 commanders. https://eduardoldrdq.estate-blog.com/36764941/new-step-by-step-map-for-7-day-pill-organizers