olymmath

HMMT November 2021 U32

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There are NN lockers, labeled from 1 to NN, placed in clockwise order around a circular hallway. Initially, all lockers are open. Ansoon starts at the first locker and always moves clockwise. When she is at locker nn and there are more than nn open lockers, she keeps locker nn open and closes the next nn open lockers, then repeats the process with the next open locker. If she is at locker nn and there are at most nn lockers still open, she keeps locker nn open and closes all other lockers. She continues this process until only one locker is left open. What is the smallest integer N>2021N>2021 such that the last open locker is locker 1?

Dataset text NuminaMath olympiads. Quoted with source.

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2046

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