318836720domain: NAppears in sequencesComposite numbers n that divide 2 * sigma(n) - d(n) [that is, 2 * sum of divisors - number of divisors].at n=17A135470Numbers k such that sigma(k) = concat(s,t) and k = s * t, where sigma(k) is the sum of the divisors of k.at n=25A272778