Numbers that reach 1 under the iterations of the map k -> k/d(k) if d(k) | k, and k -> k otherwise, where d(k) is the number of divisors of k (A000005).

A330816

Numbers that reach 1 under the iterations of the map k -> k/d(k) if d(k) | k, and k -> k otherwise, where d(k) is the number of divisors of k (A000005).