 Combinatorics - http://mathworld.wolfram.com/Combinatorics.html MathWorld article with basic definitions and links. |
 Lectures in Combinatorics - http://www.freewebs.com/desargues/combinatorics.htm An introduction to partially ordered sets, Dilworth's theorem, lattices and combinatorial geometries. |
 Catalogue of Lattices - http://www.research.att.com/~njas/lattices/ A catalogue of different types with applications to packing spheres by Neil Sloane and Gabriele Nebe. |
 Combinatorial Catalogues - http://www.csse.uwa.edu.au/~gordon/data.html Combinatorial objects such as graphs, designs and geometries collected by Gordon Royle. |
 Combinatorial Data - http://cs.anu.edu.au/~bdm/data/ Brendan McKay's collection of miscellaneous tables in graph6 or sparse6 format. |
 Polya's Enumeration Theorem - http://www.mathreference.com/cmb-gf,pet.html An article on generating functions and Polya's theory of counting by Karl Dahlke. |
 A Survey of Venn Diagrams - http://www.combinatorics.org/Surveys/ds5/VennEJC.html Various facts and figures about Venn diagrams by Frank Ruskey. |
 The Combinatorics Net - http://www.combinatorics.net/ Maintained by Bill Chen. |
 Squared Squares - http://www.squaring.net/ Tilings of squares and rectangles, the classical problem and variations. |
 The Combinatorial Object Server - http://www.theory.csc.uvic.ca/~cos/ Select a type together with specific parameter values and COS will return a list of all such combinatorial objects. |
 Counting Young Tableaux - http://bergeron.math.uqam.ca/Bessel/bessel.html An article on counting Young tableaux of bounded height by François Bergeron and Francis Gascon. |
 The Math Forum Math Library - Combinatorics - http://mathforum.org/library/topics/combinatorics/ Comprehensive catalog of websites relating to Combinatorics. |
 Encyclopedia of Combinatorial Structures - http://algo.inria.fr/encyclopedia/ Searchable database of structures with specifications and counts. |
 Enumeration of the Binary Trees - http://ulcar.uml.edu/~iag/CS/Catalan.html A note on Catalan numbers by Ivan Galkin. |
 Topics in Mathematics - Combinatorics - http://archives.math.utk.edu/topics/combinatorics.html In the Mathematics Archive at University of Tennessee, Knoxville. |
 A=B - http://www.cis.upenn.edu/~wilf/AeqB.html Downloadable combinatorics text by Marko Petkovsek, Herbert Wilf and Doron Zeilberger. Published by A. K. Peters. |
 Series Expansions - http://www.ms.unimelb.edu.au/~iwan/Series.html Iwan Jensen counts polyominoes (aka lattice animals), paths, and various related quantities. |
 ArXiv Front: CO Combinatorics - http://front.math.ucdavis.edu/math.CO Combinatorics section of the Front for the Mathematics ArXiv. |
 Extremal Combinatorics - http://www.thi.informatik.uni-frankfurt.de/~jukna/EC_Book/ With Applications in Computer Science by Stasys Jukna. |
 Generating Functions - http://www.cut-the-knot.org/blue/GeneratingFunctions.shtml Introduction to generating functions with interactive java applets by Alexander Bogomolny. |
 G-Systems - http://www.sweb.cz/vladimir_ladma/english/music/articles/dide99.htm Theory of chord structures to create music through algorithms by Vladimir Ladma. |
 Algebraic Combinatorics via Finite Group Actions - http://www.mathe2.uni-bayreuth.de/frib/html/book/hyl00.html A hypertext by A. Betten, H. Fripertinger and A. Kerber. |
 A New Proof of the Four Colour Theorem - http://www.dharwadker.org/ By Ashay Dharwadker. Includes profile, research papers for other algorithms, lecture notes, and student database. |
 Enumeration of Polyhedra - http://www.uwgb.edu/dutchs/symmetry/polynum0.htm Enumeration of polyhedra with up to 9 faces by Steven Dutch. |
 The Seventeen Wallpaper Groups - http://mathmuse.sci.ibaraki.ac.jp/pattrn/PatternE.html Examples in traditional Japanese patterns. |
 On-line Dictionary of Combinatorics - http://www.southernct.edu/~fields/comb_dic/ An expanding web text by Joe Fields. |
 The Cutting Sticks Problem - http://www.iwriteiam.nl/cutsticks.html An unsolved combinatorial problem by Frans Faase. |