MathDB
property of subset of 2001 no.s from set of 4002 no.s from 1 to 6003

Source: Dutch NMO 2001 p5

September 21, 2019
combinatoricsSubsetsEvenodd

Problem Statement

If you take a subset of 40024002 numbers from the whole numbers 11 to 60036003, then there is always a subset of 20012001 numbers within that subset with the following property: If you order the 20012001 numbers from small to large, the numbers are alternately even and odd (or odd and even). Prove this.
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