The binomial coefficient in Hayes and Stoneham is written as  


The correct formula, of course, is  


This is obviously a typo, otherwise one set of brackets would not have been necessary.  
The final result is correct anyway, because the next equation (3.5) contains the complete formula.  
Exercise 2.17 Quick Questions
Exercise 2.18 Quick Questions
Exercise 2.22 Quick Questions
© H. Föll (Defects  Script)