7 is the sole variety D for which the equation 2n − D = x2 has much more than two remedies for n and x purely natural. In particular, the equation 2n − 7 = x2 is known as the Ramanujan–Nagell equation. Polynices was one of the 7 commanders. Soon https://daltonavpny.eveowiki.com/1863733/not_known_details_about_7_day_pill_organizers