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10^{f (n)} <10n + 1 <10^{f (n) +1}

Source: OLCOMA Costa Rica National Olympiad, Final Round, 2018 3.4

September 20, 2021
functionalFunctional inequalityinequalitiesalgebra

Problem Statement

Determine if there exists a function f: NNN^*\to N^* that satisfies that for all nNn \in N^*, 10f(n)<10n+1<10f(n)+1.10^{f (n)} <10n + 1 <10^{f (n) +1}. Justify your answer.
Note: NN^* denotes the set of positive integers.