7 is the one quantity D for which the equation 2n − D = x2 has greater than two methods for n and x natural. Specifically, the equation 2n − seven = x2 is called the Ramanujan–Nagell equation. Jahannam has 7 gates which are open up continually. (Qur’an – Sura https://muqtadac948ivh8.ouyawiki.com/user