I was reading this tutorial, and I noticed it uses a seeded version of perlin noise. The one I'm using isn't seeded (it's the Improved Noise implementation of it, but ported to Godot's GDScript), and it comes with pre-made permutations, so I need to come up with random permutations so that it gives me different results based on the seed. 

I don't know how to generate the permutations though. I'm guessing there's some kind of reasoning behind those numbers that I'm not aware.

Or I need some other way of feeding it different values. Currently I'm just doing like in that tutorial, and simply giving it the x and y and a fixed float for z. 

Actually I realized now that this is easy. The original permutations are just numbers from 0 to 255. All I needed to do is shuffle them randomly...