Fibonacci Series in PHP

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<?php

function printFabonacciSeries($number){
    $a = 0; // first number of series
    $b = 1; // second number of series
    echo 'Fabonacci Series <br/>';
    echo $a.' '.$b;
    for($i=2;$i<$number;$i++){
        $c = $a + $b; //print next number of series
        echo ' '.$third;
        $a = $b;
        $b = $c;
    }
}
printFabonacciSeries(9);
?>

<?php
$number = 9;
$first = 0;
$second = 1;
echo "$first $second "; // 0 1

for($i=1;$i<= $number-2 ;$first=$second,$second=$third,$i++ ) 
{
  echo $third = $first+$second; //print next number of series
  echo " ";
}
?>