127764domain: NAppears in sequencesNumbers taking exactly 21 steps to reach 15 in A086793.at n=2A119397Numbers k such that k and uphi(k) have the same set of prime divisors, where uphi is the unitary totient function (A047994).at n=35A329859Terms of A301517 that are not exponentially odd numbers (A268335).at n=9A335989