Hofstadter G-Sequence
The sequence defined by 
and
The first few terms are 1, 1, 2, 3, 3, 4, 4, 5, 6, 6, 7, 8, 8, 9, 9, ... (Sloane's A005206).
References
Hofstadter, D. R. Gödel, Escher, Bach: An Eternal Golden Braid. New York: Vintage Books, p. 137, 1989. Sloane, N. J. A. SequenceA005206/M0436in ``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.
- Keratoid Cusp
- Kernel (Integral)
- Kernel (Linear Algebra)
- Kernel Polynomial
- Kervaire's Characterization Theorem
- Ket
- k-Form
- K-Function
- K-Graph
- Khinchin Constant
- Khintchine-Lévy Constant
- Khintchine's Constant
- Khovanski's Theorem
- Kiepert's Conics
- Kiepert's Hyperbola
- Kiepert's Parabola
- Kieroid
- Killing's Equation
- Killing Vectors
- Kimberling Sequence
- Kimberling Shuffle
- Kings Problem
- King Walk
- Kinney's Set
- Kinoshita-Terasaka Knot