Let's say I have 6 colored pencils: Pink, Purple, Yellow, Red, Blue, and Green.
I want to fill a 25-line piece of paper with text. Each line has to be one color only.
Each new line has to be a different color than the previous line. That is the only stipulation.
How many pieces of paper could I produce with a unique sequence of colors?
EDIT: Of course, this could be visualized many different ways, besides text on paper. In a nutshell, I'm looking for how many sequences of 25 items from a pool of 6 different items, where the next item in the list is different from the previous one.