use CGI qw(:standard);
print header;
print start_html;
print "<form action='$ENV{SCRIPT_NAME}' method='post'>";
print "Enter an integer: <input type='text' name='n'>";
print "<input type='submit' value='Submit'>";
print "</form>";

if (param)
{
$n = param('n');
$p = sub
{
 $sum = 1**2+2**2+3**2+4**2+5**2+6**2+7**+$n**2;
 for ('$i=0; <= $n; $i++')
{
 $sum += $i;
}
 return $sum;
};
print $p->($n);
}
print end_html;