Torsion Points under SL_2(Z/nZ) [closed]

Taking T \in E[p] and looking at the right action of SL_2(Z/pZ) on T for prime p, one can easily see that you obtain again all points in E[p] equally many times. Now what would happen when we take T \in E[n], which points do I get equally many times by the same action and which points will be taken to zero.

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I can guess what this question might mean, but I shouldn't have to. What is $E$, what is $E[n]$, etcetera? – David Speyer May 17 2011 at 20:24
-1: This question should be reworded to make it more reader-friendly (are you talking about elliptic curves?... perhaps you should mention it explicitly.) – André Henriques May 17 2011 at 21:15