<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>A4</title>
</head>
<body>
<?php
for($i = 20; $i >= 1; $i = $i - 2) {
echo $i * $i . "<br>";
}
?>
</body>
</html>
Made by Thijs Aarnoudse