MathDB
Number followers

Source: Rioplatense Olympiad 2011, Level 3, Problem 1

August 28, 2014
number theory proposednumber theory

Problem Statement

Given a positive integer nn, an operation consists of replacing nn with either 2n−12n-1, 3n−23n-2 or 5n−45n-4. A number bb is said to be a follower of number aa if bb can be obtained from aa using this operation multiple times. Find all positive integers a<2011a < 2011 that have a common follower with 20112011.
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