Notation for every odd integer number I have this equation:

$$f(x)=\tan(x)$$

I found  the vertical asymptotes to be:

$$x=\frac{\pi}{2}k$$

What is the proper notation for that k is equal to every odd number integer(negative,positive, and zero)?
$$k\in\mathbb{Z}$$ is for every integer, but is there such a symbol for every odd number integer? 
Natural numbers are positive, and sometimes zero counting numbers, my question is about integers not natural numbers.

As long as we're considering alternatives, you could always write
$$k\equiv 1\pmod 2$$
