Difference between revisions of "Main Page"

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<h2 style="border-bottom: 1px solid; color: #20458c;">New to the AoPS Wiki?</h2>
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<h2 style="border-bottom: 1px solid; color: #1b365d;">New to the AoPS Wiki?</h2>
 
   
 
   
 
If you don't know much about how to edit a wiki, you might want to read the [[AoPSWiki:Tutorial|tutorial]] and the [[Help:Contents|help files]]. You can also read [[AoPSWiki:What AoPSWiki is not|what AoPSWiki is not]]. Lastly, please read the [[AoPSWiki:Policy|policies]] of the AoPSWiki before editing, and [[AoPSWiki:What makes AoPSWiki different|why AoPSWiki is different from other online resources]].
 
If you don't know much about how to edit a wiki, you might want to read the [[AoPSWiki:Tutorial|tutorial]] and the [[Help:Contents|help files]]. You can also read [[AoPSWiki:What AoPSWiki is not|what AoPSWiki is not]]. Lastly, please read the [[AoPSWiki:Policy|policies]] of the AoPSWiki before editing, and [[AoPSWiki:What makes AoPSWiki different|why AoPSWiki is different from other online resources]].

Revision as of 15:38, 26 November 2018

Problem of the Week

1983 AIME, Problem 13

For $\{1, 2, 3, \ldots, n\}$ and each of its non-empty subsets a unique alternating sum is defined as follows. Arrange the numbers in the subset in decreasing order and then, beginning with the largest, alternately add and subtract successive numbers. For example, the alternating sum for $\{1, 2, 3, 6,9\}$ is $9-6+3-2+1=5$ and for $\{5\}$ it is simply $5$. Find the sum of all such alternating sums for $n=7$.

New to the AoPS Wiki?

If you don't know much about how to edit a wiki, you might want to read the tutorial and the help files. You can also read what AoPSWiki is not. Lastly, please read the policies of the AoPSWiki before editing, and why AoPSWiki is different from other online resources.

AoPSWiki runs on the MediaWiki software.