Knights Problem
The problem of determining how many nonattacking knights 
can be placed on an 
Chessboard. For 
,the solution is 32 (illustrated above). In general, the solutions are
giving the sequence 1, 4, 5, 8, 13, 18, 25, ... (Sloane's A030978, Dudeney 1970, p. 96; Madachy 1979).
The minimal number of knights needed to occupy or attack every square on an Chessboard is given by1, 4, 4, 4, 5, 8, 10, ... (Sloane's A006075). The number of such solutions are given by 1, 1, 2, 3, 8, 22, 3, ...(Sloane's A006076).
References
Dudeney, H. E. ``The Knight-Guards.'' §319 in Amusements in Mathematics. New York: Dover, p. 95, 1970. Madachy, J. S. Madachy's Mathematical Recreations. New York: Dover, pp. 38-39, 1979. Moser, L. ``King Paths on a Chessboard.'' Math. Gaz. 39, 54, 1955. Sloane, N. J. A. SequencesA030978,A006076/M0884and A006075/M3224in ``An On-Line Version of the Encyclopedia of Integer Sequences.''http://www.research.att.com/~njas/sequences/eisonline.html and extended entry in Sloane, N. J. A. and Plouffe, S.The Encyclopedia of Integer Sequences. San Diego: Academic Press, 1995. Vardi, I. Computational Recreations in Mathematica. Redwood City, CA: Addison-Wesley, pp. 196-197, 1991. Wilf, H. S. ``The Problem of Kings.'' Electronic J. Combinatorics 2, 3 1-7, 1995.http://www.combinatorics.org/Volume_2/volume2.html#3.
- Triangulation
- Triaugmented Dodecahedron
- Triaugmented Hexagonal Prism
- Triaugmented Triangular Prism
- Triaugmented Truncated Dodecahedron
- Triaxial Ellipsoid
- Tribar
- Tribonacci Number
- Tribox
- Trichotomy Law
- Tricolorable
- Tricomi Function
- Tricuspoid
- Tricylinder
- Tridecagon
- Trident
- Trident of Descartes
- Trident of Newton
- Tridiagonal Matrix
- Tridiminished Icosahedron
- Tridiminished Rhombicosidodecahedron
- Tridyakis Icosahedron
- Trifolium
- Trigon
- Trigonal Dipyramid