>>2112213 (pb&j)
3d Mandelbrot
https://www.youtube.com/watch?v=kaGcXUIg2qQ
Hidden areas in Julia and Mandelbrot sets (3d)
https://www.youtube.com/watch?v=vfteiiTfE0c
Times Table Modulo 200 (vid related, possibly closest to what you're thinkin' on)
https://www.youtube.com/watch?v=qhbuKbxJsk8