echo viralAdvertising(5)."\n\n";
echo viralAdvertising(10);

/* Day Shared Liked Cumulative 1 5 2 2 2 6 3 5 3 9 4 9 4 12 6 15 5 18 9 24 */ // Determines how many people have liked // the ad by the end of a given day

function viralAdvertising($n) {
	$liked = 2;
	$shared = 0;
	$cumulative = 2;

//Looping through the days

for ($i = 2; $i <= $n; $i++) {
		$shared = $liked*3;
		$liked = floor($shared/2);
		$cumulative += $liked;
	}
	return $cumulative;
}