423613domain: NAppears in sequencesComposite numbers k such that b^k == b (mod sigma(k)) for every integer b.at n=12A277286Numbers k such that sigma(k) = psi(k) + tau(k) + omega(k)^5.at n=28A391447Numbers k such that sigma(k) = psi(k) + tau(k)^2 + omega(k).at n=26A392518