sub nexti
{
	return $_[0] + 2;
}
my $o = 0;
$s = 0;
for (my $i = 1; $i <= 1001; $i = nexti($i)) {
	my $l = $o * $o + $i -1;
	my $r = $i * $i;
	
	$s += $r + $l;
	$o = $i;
}
print $s * 2 -1;