Nice. A cut down version using base-10:<p><pre><code>  X = 10**3
  print X**16&#x2F;&#x2F;(X*X-X-1)
  # 1001002003005008013021034055089144233377610
</code></pre>
It&#x27;s like a sideways addition version of the standard Haskell lazy list version:<p><pre><code>  fib = 0 : 1 : zipWith (+) fib (tail fib)</code></pre>