907039232domain: NAppears in sequencesNumbers k such that sigma(k) - tau(k) is a prime.at n=28A065061Numbers k such that sigma(k) + tau(k) and sigma(k) - tau(k) are primes.at n=13A065116Numbers k for which A327503(A046523(k)) differs from A327503(k).at n=19A351948Powers k^m, m > 2, where k is an Achilles number.at n=13A390436