MathDB
2022 Putnam B2

Source:

December 4, 2022
PutnamPutnam 2022

Problem Statement

Let ×\times represent the cross product in R3.\mathbb{R}^3. For what positive integers nn does there exist a set S⊂R3S \subset \mathbb{R}^3 with exactly nn elements such that S={v×w:v,w∈S}?S=\{v \times w: v, w \in S\}?
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