title: Excel: Insert new line every x rows with content according to a pattern
body: <p>I have a long list in excel with two columns. Every 26 rows, I want to insert two new lines, pushing the remaining rows further down. So basically I have</p>
  
  <pre><code>26   ABC
  27   DEF
  28   GHI
  </code></pre>
  
  <p>and want to make it</p>
  
  <pre><code>26   ABC
  27
  28
  29   DEF
  30   GHI
  </code></pre>
  
  <p>Additionally, if it's possible, I'd like to put text into those new lines according to a simple pattern:</p>
  
  <pre><code>1_sometext
  1_someothertext
  
  2_sometext
  2_someothertext
  </code></pre>
  
  <p>So the ones starting with "1_" would go into rows 27 and 28, the ones starting with "2_" would go into rows 55 and 56, and the number keeps incrementing. </p>