title: Find the Kth least number for expression (2^x)*(3^y)*(5^z)
body: <p>In the expression </p>
  
  <blockquote>
    <p>2<sup>x</sup> * 3<sup>y</sup> * 5<sup>z</sup></p>
  </blockquote>
  
  <p>The <code>x</code>, <code>y</code> and <code>z</code> can take non negative integer value (>=0). </p>
  
  <p>So the function would generate a series of number <code>1,2,3,4,5,6,8,9,10,12,15,16....</code></p>
  
  <ul>
  <li>I have a brute force solution. </li>
  <li>I would basically iterate in a loop starting with 1 and in each iteration I would find if the current number factors are only from the set of 2,3 or 5. </li>
  </ul>
  
  <p>What I would like to have is an elegant algorithm. </p>
  
  <p>This is an interview question. </p>