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.
- Omega Constant
- Omega Function
- Omino
- Omnific Integer
- O'Nan Group
- Onduloid
- One
- One-Form
- One-Mouth Theorem
- One-Ninth Constant
- One-to-One
- One-Way Function
- Only Critical Point in Town Test
- Onto
- Open Disk
- Open Interval
- Open Map
- Open Mapping Theorem
- Open Set
- Operad
- Operand
- Operational Mathematics
- Operations Research
- Operator
- Optimization Theory