the hard ones are unsolved research problems?
I haven't read the book, so he poses research questions as exercises to the reader...?
I haven't read the book, so he poses research questions as exercises to the reader...?
"Develop computer programs for simplifying sums that involve binomial coefficients"
Which was solved in the book titled "A = B":
https://www2.math.upenn.edu/~wilf/AeqB.html
or
He's like a depth-first system guy... I suspect he only planned the 7 volumes because it was a requirement to start out wide.