MathDB
Max + Lewis = Fight?

Source: Brazil EGMO TST 2023 #3

November 10, 2022
combinatorics

Problem Statement

There are nn cards. Max and Lewis play, alternately, the following game Max starts the game, he removes exactly 11 card, in each round the current player can remove any quantity of cards, from 11 card to t+1t+1 cards, which tt is the number of removed cards by the previous player, and the winner is the player who remove the last card. Determine all the possible values of nn such that Max has the winning strategy.