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<head>
  <meta charset="utf-8">
  <title>JS Number Pattern 62 - Try It (Compact)</title>
</head>
<body>
  <h1>Perfect Square Spiral (4×4)</h1>
  <p>Edit <code>n</code> and click Run.</p>
  <pre id="output"></pre>
  <script>
    const n = 4;
    const a = Array.from({ length: n }, () => Array(n).fill(0));
    let top = 0;
    let bottom = n - 1;
    let left = 0;
    let right = n - 1;
    let val = 1;
    let result = "";

    while (top <= bottom && left <= right) {
      for (let j = left; j <= right; j++) a[top][j] = val++;
      top++;
      for (let i = top; i <= bottom; i++) a[i][right] = val++;
      right--;
      if (top <= bottom) {
        for (let j = right; j >= left; j--) a[bottom][j] = val++;
        bottom--;
      }
      if (left <= right) {
        for (let i = bottom; i >= top; i--) a[i][left] = val++;
        left++;
      }
    }

    for (const row of a) {
      result += row.map(cell => String(cell).padStart(4, " ")).join("") + "\n";
    }

    document.getElementById("output").textContent = result;
  </script>
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JavaScript Number Pattern 62 (Try It — Compact)