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Existence of monotonic perfect square

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December 31, 2011
number theory unsolvednumber theory

Problem Statement

A positive integer is called monotonic if when written in base 1010, the digits are weakly increasing. Thus 1222677812226778 is monotonic. Note that a positive integer cannot have first digit 00. Prove that for every positive integer nn, there is an nn-digit monotonic number which is a perfect square.