411138domain: NAppears in sequencesNumbers n such that there exists an x!=n that makes {n,n,x} an amicable multiset.at n=19A259302Abundant numbers n such that sigma(sigma(n) - 2*n) = sigma(n).at n=21A292365Integers k such that there exists an integer 0<m<k such that sigma(k) = sigma(m) = m + 2*k.at n=10A383239