157608domain: NAppears in sequencesTrajectory of 397 under the map A340008: n -> n/2 if n is even, n-> n^2 - 1 if n is an odd prime, otherwise n -> n - 1.at n=1A340419Integers k such that there exists an integer 0<m<k such that (1/sigma(m)^2 + 1/sigma(k)^2)*(m+k)^2 = 1.at n=34A383964