a(1)=1. For n>1, start with n, concatenate the indices of its prime factors, and repeat until either (i) a prime p is reached, when we set a(n)=p; or (ii) the process enters a loop of length m, when we set a(n) = -m; or (iii) the trajectory diverges to infinity, when we set a(n) = 0.

A282770

a(1)=1. For n>1, start with n, concatenate the indices of its prime factors, and repeat until either (i) a prime p is reached, when we set a(n)=p; or (ii) the process enters a loop of length m, when we set a(n) = -m; or (iii) the trajectory diverges to infinity, when we set a(n) = 0.