4491589domain: NAppears in sequencesSmallest nonprime number which if used as initial term for iteration of the A000010[x] function, results in list-to-fixed-point of length=n, or 0 if no such number exists.at n=23A098196Smallest k such that phi(phi(k)) = 2^n, where phi is the Euler totient function.at n=20A184968