Chapter 2 Page 25 Example 2.4, line 1. Change "a_0=1" to "a_0=0", and let change "a_n=2^{n-1}" into "a_n=2^n-1". Chapter 3 Page 47. In the table the last box in the third row replace the k! by (n-k)! Page 51: After the first sentence of Exercise 24, insert the following sentence "Let $H_3(r)$ be the number of magic squares of size $3\times 3$ in which each row and column have sum $r$." (THIS IS VERY IMPORTANT) Chapter 4 Page 76, Exercise 16(a): Change "k" to "x" to agree with answer. Page 77, Exercise 18: Change the exponent of (-1) to a_2. Page 77 Line -1 from the bottom : add x^n at the end of the formula, right after {2n \choose n} Chapter 5 The words "Composition" and "Weak Composition" should be interchanged throughout the chapter. Page 92, Line 3. Interchange the words "singleton" and "doubleton". The line should read "consist of one doubleton and $n-2$ singletons." Chapter 6 page115 Line no.2, the right-hand side of the formula: change "a_{n-1 , k }" to "(n-1)a_{n-1 , k }" Chapter 7 Page 139, Exercise 13. Replace the last sentence by "Compute the number of $n$-permutations whose excedance set contains at least one of $n-2$ and $n-1$. " Page 143, Solution of (13), the above exercise. Replace the entire solution by the following. "Let $f(S)$ be the number of $n$-permutations whose excedance set {\em contains} $S$. Then we have $f(n-1)=(n-1)!$ as in such permutations, the entry $n$ must be in position $n-1$. We also have $f(n-2)=2(n-1)!$ as in permutations enumerated by $f(n-2)$, either the entry $n-1$ or the entry $n$ has to be in position $n-2$. Finally, we have $f(n-2,n-1)=(n-2)!$ as in such permutations, the entry $n$ must be in position $n-1$, and the entry $n-1$ must be in position $n-2$. Therefore, by the sieve formula, there are $f(n-1)+f(n-2)-f(n-2,n-1)=3(n-1)!-(n-2)!$ permutations with the required property. " Chapter 8 pg164 Line no.9, 14, 17 from the top : change "ordinary" to "exponential" Page 165, line -7; (the last formula of the page) In the second term, the exponent of e should be \ln(\frac{1}{1-x}). In other words, remove the "-x" the is in the same parenthese Chapter 14 page 311 -15 and -16 from the bottom : Change "k^{n-1}" to "(k-1)^n" (both times) Chapter 16 Page 388, Example 16.18: Replace "c_n" by "c_{n-1}".