D-Number
A Natural Number 
such that
whenever
(
and 
are Relatively Prime) and 
. There are an infinite number of such numbers,the first few being 9, 15, 21, 33, 39, 51, ... (Sloane's A033553).See also Knödel Numbers
References
Makowski, A. ``Generalization of Morrow's Sloane, N. J. A. Sequence A033553in ``The On-Line Version of the Encyclopedia of Integer Sequences.''http://www.research.att.com/~njas/sequences/eisonline.html.
-Numbers.'' Simon Stevin 36, 71, 1962/1963.
- Heuman Lambda Function
- Heun's Differential Equation
- Heuristic
- Hexa
- Hexabolo
- Hexacontagon
- Hexacronic Icositetrahedron
- Hexad
- Hexadecagon
- Hexadecimal
- Hexaflexagon
- Hexagon
- Hexagonal Number
- Hexagonal Pyramidal Number
- Hexagonal Scalenohedron
- Hexagonal Tiling
- Hexagon Polyiamond
- Hexagram
- Hexagrammum Mysticum Theorem
- Hexahedron
- Hexahemioctahedron
- Hexakaidecagon
- Hexakis Icosahedron
- Hexakis Octahedron
- Hex Game