The Sierpinski Arrowhead Curve is a curve that's limit is Sierpinski's Triangle.
It first starts like this:
_ / \
Then, each line is replaced with a rotated version of the first one:
_ / \ \ / _/ \_
_ / \ \ / _/ \_ / \ \_ _/ _ \ / _ / \_/ \_/ \
Given a number n, output the n-th iteration of the Sierpinski Arrowhead Curve.
You may choose 0 or 1-indexed input, but please specify that in your answer.
You may generate an image, or use Ascii Art in the format I have given above.
You may not use built-ins to generate this curve.
Remember, this is code-golf, so the code with the fewest bytes wins.