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There are exactly 116 different groups P where $7\mathbf{Z}^{3} \subset P \subset \mathbf{Z}^{3}$

I don't know how to prove this. Is it provable at all? How?

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    Count the number of subgroups of the quotient $\mathbb Z^3/7\mathbb Z^3$.2011-12-08

2 Answers 2