7 is the one range D for which the equation 2n − D = x2 has much more than two options for n and x pure. In particular, the equation 2n − seven = x2 is referred to as the Ramanujan–Nagell equation. Naturally There exists also the effectively-known Tale of https://non-slipslippersforelderl29744.blogrelation.com/44220434/the-7-day-pill-organizers-diaries