So FerretBoy, what you're saying is that the program is only reporting numbers of individual close pairs, rather than clustered groups.

I expect to hear pairs rather often. It's clustered groups that I'm interested in.

Here's another idea. Something I've toyed with the idea of making myself. A program that shows, by color graph, the distribution of a given album in the shuffle:



(Pictures are a 60x60 grid=3600 songs. Images doubled in size so you could see the red dots.)

What I'm interested in seeing is... in a truly random shuffle, how often the second thing actually should happen. Not just what we think we perceive if we happen to hear three Madonna songs on the same trip.