7 is the only real range D for which the equation 2n − D = x2 has greater than two answers for n and x normal. Particularly, the equation 2n − seven = x2 is known as the Ramanujan–Nagell equation. 2 hrs back By Mashable Staff A MacBook Professional for https://senioraidtools.com/10-easy-mobility-exercises-for-seniors-to-stay-active-and-independent/