> if n≥1000, f(n) < n And this is what makes the setup not very interesting. Compare with 3x+1 problem, where the sequence can grow, but eventually comes down

> if n≥1000, f(n) < n And this is what makes the setup not very interesting. Compare with 3x+1 problem, where the sequence can grow, but eventually comes down (there's a simple probabilistic argument for that, but no formal proof).