How would I express the series $|1+1+1|+|1+1-1|+|1-1+1|+|1-1-1|+|-1+1+1|+|-1+1-1|+|-1-1+1|+|-1-1-1|$ in summation notation? I tried putting the series
$$
|1+1+1|+|1+1-1|\\+|1-1+1|+|1-1-1|\\+|-1+1+1|+|-1+1-1|\\+|-1-1+1|+|-1-1-1|
$$
into Wolfram Alpha and typing "in summation notation" but it wouldn't tell me what it is in summation notation.  I tried to figure it out on my own but I can't figure out how to put this series into summation notation.
How would I express this sequence in summation notation?

$\sum_{i,j,k=0}^1 | (-1)^i + (-1)^j + (-1)^k |$
