I'm reading Donald Knuth's The Art of Programming. I can't figure out how to apply chi-square. Here's the algorithm itself enter image description here enter image description here
Let's say I have a sequence 1101221022120202001212201010201121. Then I "collect coupons" and get this array [5,3,5,5,6,5,5,5,4]. Further what to do with this array I do not understand. How to apply chi-square and what are these probabilities (pr and pt) for?