title: How to ask mathematica to compute higher order derivatives evaluated at 0
body: <p>I have a function, let's say for example, </p>
  
  <pre><code>D[x^2*Exp[x^2], {x, 6}] /. x -&gt; 0
  </code></pre>
  
  <p>And I want to replace 6 by a general integer <code>n</code>,</p>
  
  <p>Or cases like the following:</p>
  
  <pre><code> Limit[Limit[D[D[x /((-1 + x) (1 - y) (-1 + x + x y)), {x, 3}], {y, 5}], {x -&gt; 0}], {y -&gt; 0}]
  </code></pre>
  
  <p>And I want to replace 3 and 5 by a general integer <code>m</code> and <code>n</code> respectively.</p>
  
  <p>How to solve these two kinds of problems in general in mma?</p>
  
  <p>Many thanks.</p>