7 is the one selection D for which the equation 2n − D = x2 has greater than two options for n and x all-natural. Specifically, the equation 2n − seven = x2 is referred to as the Ramanujan–Nagell equation. 2 hrs in the past By Mashable Workforce A MacBook https://mariodtdpc.wikiadvocate.com/7192869/5_simple_statements_about_7_day_pill_organizers_explained