Spoiler for off topic reply to Cat Megex:
It was in the second episode, as Kaisos said. Actually, it was inspired by
Getter Robo. At least that's what the fansubs lead me to think ("Change! Getter!").
In other news... here's an image found by Dangoz (my brother) on some sort of mathematics competition ranking site. I have the line of interest highlighted.
Call it 'shopped if you like, but it's real.