Factorial, but with addition Is there a notation for addition form of factorial?
$$5! = 5\times4\times3\times2\times1$$
That's pretty obvious. But I'm wondering what I'd need to use to describe
$$5+4+3+2+1$$
like the factorial $5!$ way.
EDIT: I know about the formula. I want to know if there's a short notation.

$\sum_{n=1}^{k} n = 1 +2+3+\ldots+k$. Is a nice notation for it. So 
$$1 + 2 + 3 + 4 + 5 = \sum_{n=1}^{5} n$$.
