title: strange behaviour of maple when computing a sum with modulo
body: <p>I have defined a simple function:</p>
  
  <pre><code>c(n) = 2 * floor((n mod 24) / 12)
  </code></pre>
  
  <p>I want to compute the sum c(0) + c(1) + ... + c(n) with Maple, but the sums Maple computes are wrong. Here is a screenshot of an example showing an obviously wrong sum: <a href="http://i.stack.imgur.com/BpmB2.png" rel="nofollow">http://i.stack.imgur.com/BpmB2.png</a></p>
  
  <p>I don't know what i am missing here ...</p>
  
  <p>Thank you for your time</p>