czech republic,czech and slovakia MO(third round),2008 p4
Source:
February 25, 2012
modular arithmeticcalculusnumber theory proposednumber theory
Problem Statement
In decimal representation, we call an integer -carboxylic if and only if it can be represented as a sum of distinct integers, all of them greater than , whose digits are the same. For instance, is -carboxylic because . Find, with an example, the smallest integer such that is -carboxylic.