Triangle Tiling
The total number of triangle (including inverted ones) in the above figures is given by
The first few values are 1, 5, 13, 27, 48, 78, 118, 170, 235, 315, 411, 525, 658, 812, 988, 1188, 1413, 1665, ... (Sloane's A002717).
References
Conway, J. H. and Guy, R. K. ``How Many Triangles.'' In The Book of Numbers. New York: Springer-Verlag, pp. 83-84, 1996. Sloane, N. J. A. SequenceA002717/M3827in ``An On-Line Version of the Encyclopedia of Integer Sequences.''http://www.research.att.com/~njas/sequences/eisonline.html and Sloane, N. J. A. and Plouffe, S.The Encyclopedia of Integer Sequences. San Diego: Academic Press, 1995.
- Heegaard Diagram
- Heegaard Splitting
- Heegner Number
- Heesch Number
- Heesch's Problem
- Height
- Heilbronn Triangle Problem
- Heine-Borel Theorem
- Heine Hypergeometric Series
- Heisenberg Group
- Heisenberg Space
- Held Group
- Helen of Geometers
- Helicoid
- Helix
- Helly Number
- Helly's Theorem
- Helmholtz Differential Equation
- Helmholtz Differential Equation--Bipolar Coordinates
- Helmholtz Differential Equation--Cartesian Coordinates
- Helmholtz Differential Equation--Circular Cylindrical Coordinates
- Helmholtz Differential Equation--Confocal Ellipsoidal Coordinates
- Helmholtz Differential Equation--Confocal Paraboloidal Coordinates
- Helmholtz Differential Equation--Conical Coordinates
- Helmholtz Differential Equation--Elliptic Cylindrical Coordinates