I am currently reading the [Algorithm Design Manual](http://www.algorist.com/), but my mathematical notation has become a little rusty.

What does

!["\left( a \ b \right)" LaTeX](https://chart.apis.google.com/chart?cht=tx&chl=%5CLARGE%5C%21%5Cleft%28%20a%20%20%5C%5C%20b%20%5Cright%29)

mean?