Wolfram Research
Wolfram Math World: Discrete Mathematics Topics List
A thorough list of topics in the study of Discrete Mathematics. Combinatorics, Graph Theory, and Point Lattices are three of the many areas given in-depth explanations here. Many of the links contain discussions of the topics that both...
Wolfram Research
Wolfram Math World: Recursive Function
A definition of recursive function, and the relation of recursive function to recursion. There is also an example defining f(x,y) as the function xy.
Wolfram Research
Wolfram Math World: Recursive Sequence
Defining recursive sequence, this site also discussed the relationship of Fibonacci numbers and recursive sequence.