Erdős Problem #412 — Intersections of iterated divisor-sum orbits

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Let σ1(n)=σ(n)\sigma_1(n)=\sigma(n), the sum of divisors function, and σk(n)=σ(σk−1(n))\sigma_k(n)=\sigma(\sigma_{k-1}(n)). Is it true that, for every m,n≥2m,n\geq 2, there exist some i,ji,j such that σi(m)=σj(n)\sigma_i(m)=\sigma_j(n)?

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