seven is the one number D for which the equation 2n − D = x2 has a lot more than two methods for n and x purely natural. Especially, the equation 2n − seven = x2 is known as the Ramanujan–Nagell equation.Obviously there is also the very well-acknowledged Tale of Pharaohs dream concerning the 7 Body fat cows and 7 thin cows.In case you recogni