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<head>
  <meta charset="utf-8">
  <title>JS Number Pattern 24 - Try It (Safe Input)</title>
</head>
<body>
  <h1>Centered Pyramid (Safe Input)</h1>
  <p>Enter a valid positive width when prompted (re-prompts on bad input), then click Run.</p>
  <pre id="output"></pre>
  <script>
    let maxN = 0;
    let messages = "";

    while (maxN < 1) {
      const maxInput = prompt("Enter the maximum odd width:");
      maxN = parseInt(maxInput, 10);
      if (!Number.isFinite(maxN) || maxN < 1) {
        maxN = 0;
        messages += "Please enter a positive whole number.\n";
      }
    }

    if (maxN % 2 === 0) {
      maxN--;
    }

    let k = 1;
    let result = messages;
    for (let i = 1; i <= maxN; i += 2) {
      let line = "";
      for (let j = maxN; j >= 1; j--) {
        if (j > i) {
          line += " ";
        } else {
          line += k + " ";
          k++;
        }
      }
      result += line + "\n";
    }

    document.getElementById("output").textContent = result;
  </script>
</body>
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JavaScript Number Pattern 24 (Try It — Safe Input)