579667086domain: NAppears in sequencesNumbers k such that sigma(k) = Sum_{j|k, j<k} sigma(j).at n=7A066218Numbers k such that sigma(k) divides Sum_{d|k} sigma(d).at n=20A221219Numbers k such that if x = Sum_{j|k, j<k} (sigma(j) - j) then k = Sum_{j|x, j<x} (sigma(j) - j).at n=13A238765