MathDB
n bulbs on a line, on off

Source: Mathematics Regional Olympiad of Mexico West 2018 P6

September 8, 2022
combinatorics

Problem Statement

Let n>1n > 1 be a natural number. There are nn bulbs in a line, each of which can be on or off. Every minute, simultaneously, all the lit bulbs turn off and the unlit bulbs that were adjacent to exactly one lit bulb turn on. Determine for what values of nn there is an initial arrangement such that if this process is followed indefinitely, all the lights will never be off.