Seven is the sole variety D for which the equation 2n − D = x2 has more than two answers for n and x pure. Particularly, the equation 2n − seven = x2 is known as the Ramanujan–Nagell equation. Not everyone thinks that cats have nine life. In some aspects https://best-pool-exercise-equipm51693.therainblog.com/36586047/everything-about-7-day-pill-organizers