Deret Fibonacci

<html>
<head><title> Coba PHP </title></head>
	<body>
		<?php

 		$a;
		$n=16;
		$f=1;
		$f2=1;
		$fibo;

		echo "<br>Deret Fibonacci -> 1 ";
			for($a=1;$a<=$n-2;$a++)
         	{
				echo "$f2 &nbsp;";
				$fibo=$f+$f2;
            	$f = $f2;
            	$f2 = $fibo;
			}
		echo"$fibo &nbsp;";

		?>
	</body>
</html>