Sorry about that previous post. I just wanted to show how easy it is to come up with theories when you combine things at random.
There was a certain idea and logic behind it. We have seven notes and seven colors (three times green), so a certain note can correspond to a certain color. 780 I thought was infrared. Not in the visible light area.
Maybe the equivalent, however, is just Clue 5, or Super Solution. It should be investigated.