I needed a system that changed the color every other (persistent) particle.
This is how it worked for me.
ok, since this small screenshot does seem to not explain all too well.
here some walkthrough:
- just go to "initialize particle"
- then press the right rollout in the color section and set it to "select linear color from array"
- then press the right rollout in the "direct array index" and set it to "return particle ID attributes"