-1,1,-1,1 how does this series work ?

-1,1,-1,1 how does this series work

$$(-1)^n \quad n\in$$

If you plot them both, they would land in the same place.

Hope that the images help!

You're just multiplying by -1:

(1 x -1) = -1

(-1 x -1) = 1

(1 x -1) = -1

(-1 x -1) = 1

And so on.