7 is the sole range D for which the equation 2n − D = x2 has greater than two solutions for n and x pure. Especially, the equation 2n − seven = x2 is called the Ramanujan–Nagell equation. Jahannam has seven gates which happen to be open continually. (Qur’an – https://non-slip-slippers-for-eld52604.suomiblog.com/how-much-you-need-to-expect-you-ll-pay-for-a-good-7-day-pill-organizers-53495264