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  <title>Happy numbers — range</title>
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  <h1>Happy numbers in [1, 50]</h1>
  <p>Uses the same helpers as the tutorial. <strong>Run</strong> to print.</p>
  <pre id=out></pre>
  <script>!function(){function n(n){for(var r=0;n>0;){var t=n%10;r+=t*t,n=Math.floor(n/10)}return r}function r(r){for(var t={},o=r;1!==o;){if(t[o])return!1;t[o]=!0,o=n(o)}return!0}var t=[];t.push("Happy numbers in the range 1 to 50:");var o,e=[];for(o=1;o<=50;o++)r(o)&&e.push(String(o));t.push(e.join(" ")),document.getElementById("out").textContent=t.join("\n")}()</script>
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JavaScript Happy Numbers — Range 1–50 (Try It)