# ThreeNPlus1 solution

<?php
/*
* Created on Feb 13, 2008
*
* In class example.
* Write a PHP script that computes the 3N+1 problem. For N > 0,
* generate a sequence of numbers using the following simple rules:
* if N is even, divide it by 2; if N is odd, multiply it by 3 and add 1.
* The sequence always converges to 1, although the length of the sequence
* varies depending on the choice of N.
*
*/
?>
<HTML>
<HEAD>
<TITLE>3N + 1 Problem</TITLE>
</HEAD>
<BODY>
<H4>The 3N + 1 Problem</h4>
<?php
$n = 8;
echo "N= $n<BR>";
while ($n > 1) { // While n is greater than 1
echo "$n<BR>"; // Print it then either
if ($n % 2 == 0) {
$n = $n / 2; // Divide it by 2
}
else {
$n = 3 * $n + 1; // Or multiply 3N+1
}
}
?>
</BODY>
</HTML>