Erdős Problem #410 — Growth of iterated divisor sums

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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 all n≥2n\geq 2 lim⁡k→∞σk(n)1/k=∞?\lim_{k\to \infty} \sigma_k(n)^{1/k}=\infty?

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