Tried to solve the problem of a week, and only asked the question, he decided.
It is necessary to show formula in a single line, by default all editors divide the lines! That is, to do so:
$$\left|\begin{array}{ccc} 1 & … & n\\ … & … & …\\ n & … & n \end{array}\right|$$
Thanks for a great product!
Add the following characters < B R/>
