CollapseProblem 414Let h1(n)=h(n)=n+τ(n)h_1(n)=h(n)=n+\tau(n)h1(n)=h(n)=n+τ(n) (where τ(n)\tau(n)τ(n) counts the number of divisors of nnn) and hk(n)=h(hk−1(n))h_k(n)=h(h_{k-1}(n))hk(n)=h(hk−1(n)). Is it true, for any m,nm,nm,n, there exist iii and jjj such that hi(m)=hj(n)h_i(m)=h_j(n)hi(m)=hj(n)?Source: erdosproblems.com/414Number theoryIterated functionsWiki pageStatusOpenNo claim settles this problem.