MathDB

5

Part of 2007 Portugal MO

Problems(1)

there are houses of at least five different colors.

Source: Portugal OPM 2007 p5

5/19/2024
Rua do Antonio has 100100 houses numbered from 11 to 100100. Any house numbered with the difference between the numbers of two houses of the same color is a different color. Prove that on Rua do Antonio there are houses of at least five different colors.
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