MathDB
last numbers on board from 1-2013

Source: 2013 Argentina OMA Finals L3 p5

January 15, 2023
combinatoricsalgebra

Problem Statement

Given several nonnegative integers (repetitions allowed), the allowed operation is to choose a positive integer aa and replace each number bb greater than or equal to aa by bāˆ’ab-a (the numbers aa , if any, are replaced by 00). Initially, the integers from 11 are written on the blackboard until 20132013 inclusive. After a few operations the numbers on the board have a sum equal to 1010. Determine what the numbers that remained on the board could be. Find all the possibilities.