[cousin_it]

It's very simple. Basically you need to cycle through all n-bit integers (except zero) in a random-looking way, and it turns out there's an arcane-ish bit twiddling operation that will do it when applied repeatedly. The reason it works can be explained with some undergrad math. You don't need to know these things for business programming but they are fun to read about.

Another idea in a similar vein is https://en.wikipedia.org/wiki/Floyd%E2%80%93Steinberg_dither... It converts an image with many shades of gray to an image with only black and white pixels. The algorithm is dead simple, but the results are surprisingly convincing.