The maximal number of terms that could remain on their place
Source: Tournament of Towns Spring 2003 - Senior O-Level - Problem 4
June 14, 2011
number theory proposednumber theory
Problem Statement
In the sequence the terms are rearranged so that each term is obtained from the previous one by increasing or decreasing one of its digits by (for example, can be followed by , or , but not by or ). What is the maximal number of terms that could remain on their places?