7 is the only real range D for which the equation 2n − D = x2 has in excess of two solutions for n and x all-natural. Especially, the equation 2n − seven = x2 is known as the Ramanujan–Nagell equation. 2 hours back By Mashable Crew A MacBook Professional https://andersonghkvn.digiblogbox.com/62255559/7-day-pill-organizers-things-to-know-before-you-buy