Seven is the sole number D for which the equation 2n − D = x2 has in excess of two alternatives for n and x purely natural. In particular, the equation 2n − 7 = x2 is called the Ramanujan–Nagell equation. Quite a few Jews may perhaps wear a torn, https://johnathanjboal.wikibyby.com/1831026/how_7_day_pill_organizers_can_save_you_time_stress_and_money