PHP: Large sumLongest Collatz sequence - ProjectEuler Problem #14

PHP: Longest Collatz sequence.php

<?php
function sequence($start, $step = 0)
{
	while($start != 1)
	{
		if($start % 2 == 0)
			$start = $start / 2;
		else
			$start = 3*$start + 1;
		$step++;
	}
	return $step;
}

for($i = 1000000; $i > 1; $i--)
{
	$all_steps[$i] = sequence($i);
}

$max = array_keys($all_steps, max($all_steps));
echo 'Number: '.$max[0].' Chain: '.$all_steps[$max[0]];