The freely available [1] is a nice supplement to some of the material in Concrete Mathematics, and this [2] is an approachable introduction to graph theory with

The freely available [1] is a nice supplement to some of the material in Concrete Mathematics, and this [2] is an approachable introduction to graph theory with side notes on both proof techniques and algorithms. More generally, if you're not already comfortable with linear algebra (a couple college semesters "or equivalent experience"), I'd recommend both [3] and [4] for two entirely different perspectives. For modern algebra more generally, I'm a huge fan of [5]. If I could only take one introductory mathematics book to a desert island, I'd cheat a bit and take [6], [7], and [8]. While never directly involved in CS, Courant was very interested in the practical applications of theoretical mathematics, see, e.g., [9] and, well, most everything else he wrote. I could go on and on, so I'll stop here. [1] http://www.math.upenn.edu/~wilf/DownldGF.html http://www.math.upenn.edu/~wilf/DownldGF.html [2] http://www.amazon.com/Graph-Theory-Graduate-Texts-Mathematics/dp/1846289696 http://www.amazon.com/Graph-Theory-Graduate-Texts-Mathematic... [3] http://www.amazon.com/Linear-Algebra-Applications-Gilbert-Strang/dp/0155510053 http://www.amazon.com/Linear-Algebra-Applications-Gilbert-St... [4] http://www.amazon.com/Finite-Dimensional-Vector-Spaces-P-R-Halmos/dp/0387900934 http://www.amazon.com/Finite-Dimensional-Vector-Spaces-P-R-H... [5] http://www.amazon.com/Algebra-Chelsea-Publishing-Saunders-Lane/dp/0821816462 http://www.amazon.com/Algebra-Chelsea-Publishing-Saunders-La... [6] http://www.amazon.com/Introduction-Calculus-Analysis-Classics-Mathematics/dp/354065058X http://www.amazon.com/Introduction-Calculus-Analysis-Classic... [7] http://www.amazon.com/Introduction-Calculus-Analysis-Classics-Mathematics/dp/3540665692 http://www.amazon.com/Introduction-Calculus-Analysis-Classic... [8] http://www.amazon.com/Introduction-Calculus-Analysis-Classics-Mathematics/dp/3540665706 http://www.amazon.com/Introduction-Calculus-Analysis-Classic... [9] http://www.ams.org/journals/bull/1943-49-01/S0002-9904-1943-07818-4/S0002-9904-1943-07818-4.pdf http://www.ams.org/journals/bull/1943-49-01/S0002-9904-1943-...