Guy's Conjecture
Guy's conjecture, which has not yet been proven or disproven, states that the Crossing Number for a Complete Graph of order 
is
where
is the Floor Function,which can be rewritten
The first few values are 0, 0, 0, 0, 1, 3, 9, 18, 36, 60, ... (Sloane's A000241). See also Crossing Number (Graph)
References
Sloane, N. J. A. SequenceA000241/M2772in ``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.
- Primitive Root of Unity
- Primitive Semiperfect Number
- Primitive Sequence
- Primorial
- Prince Rupert's Cube
- Principal
- Principal Curvatures
- Principal Curve
- Principal Direction
- Principal Ideal
- Principal Normal Vector
- Principal Quintic Form
- Principal Radius of Curvature
- Principal Value
- Principal Vector
- Principal Vertex
- Principle
- Pringsheim's Theorem
- Printer's Errors
- Prior Distribution
- Prism
- Prismatic Ring
- Prismatoid
- Prismoid
- Prisoner's Dilemma