7 is the only quantity D for which the equation 2n − D = x2 has over two alternatives for n and x pure. Particularly, the equation 2n − seven = x2 is referred to as the Ramanujan–Nagell equation. Being an early key selection inside the series of good integers, https://my-social-box.com/story13774470/how-7zean-can-save-you-time-stress-and-money