24234722domain: NAppears in sequencesNumbers k such that sigma(k) + tau(k) is a prime.at n=16A064205a(n) = 2*prime(n)^4.at n=16A172191a(n) = least value of k such that tau(k) = A000594(k) == n mod 23.at n=18A278578Terms of A330606 which are not squares or powers of 2.at n=26A330650