7 is the only real range D for which the equation 2n − D = x2 has more than two options for n and x normal. In particular, the equation 2n − 7 = x2 is referred to as the Ramanujan–Nagell equation. Not Everybody believes that cats have nine lives. https://brooksqjykw.jaiblogs.com/64786388/facts-about-7-day-pill-organizers-revealed