On the 1st day of Xmas, my true love gave to me:
1 item
On the 2nd day of Xmas, my true love gave to me:
2 items + 1 item
On the 3rd day of Xmas, my true love gave to me:
3 items + 2 items + 1 item
.
.
On the n-1 day of Xmas, my true love gave to me:
n-1 items + n-2 items + ... + 1 item
On the nth day of Xmas, my true love gave to me:
n items + n-1 items + ... + 1 item
How many total items did my true love give to me, as a function of n?
The Anonymous Bureaucrat,
and frankly, quite content not to be
a member of either major US political party.