And a partridge in a pear treeLevel pending
As the well known song goes, on the first day of christmas my true love gave to me a partridge in a pear tree. On the second day of Christmas my true love gave to me 2 turtle doves and a partridge in a pear tree. On day n she gives me 1 of something, 2 of something else, ... , n of something else. At the end of the first 16 days how many gifts has my true love given to me in total?