7 is the one amount D for which the equation 2n − D = x2 has in excess of two methods for n and x purely natural. Particularly, the equation 2n − 7 = x2 is named the Ramanujan–Nagell equation. The island of Ogygia was the house of The gorgeous https://zandernbkry.dm-blog.com/37833871/everything-about-7-day-pill-organizers