MathDB
Process combo

Source: CMO 2022 P3

March 12, 2022
combinatorics

Problem Statement

Vishal starts with nn copies of the number 11 written on the board. Every minute, he takes two numbers a,ba, b and replaces them with either a+ba+b or min(a2,b2)\min(a^2, b^2). After n1n-1 there is 11 number on the board. Let the maximal possible value of this number be f(n)f(n). Prove 2n/3<f(n)3n/32^{n/3}<f(n)\leq 3^{n/3}.