title: Show that the summation ∑ i to n (logi) is O(nlogn)
body: <p>One way I thought it works is that we can say that  <code>∑_i^{n (log i)} &lt; ∑_i^{n (log n)}</code> and then try to argue that it's O(n log n), but where to go from here? Any suggestions?</p>