Definition:Code Number for Integer

Definition
Let $x \in \Z$ be an integer.

If $x > 0$, then let:
 * $n = 2 x - 1$

If $x \le 0$, then let:
 * $n = -2 x$

Then, $n \in \N$ codes the integer $x$, or $n$ is the code number for the integer $x$.