MathDB
Removing successive numbers from an interval.

Source: Baltic Way 2018, Problem 10

November 6, 2018
combinatoricssets of integers

Problem Statement

The integers from 11 to nn are written, one on each of nn cards. The first player removes one card. Then the second player removes two cards with consecutive integers. After that the first player removes three cards with consecutive integers. Finally, the second player removes four cards with consecutive integers. What is th smallest value of nn for which the second player can ensure that he competes both his moves?