Doubly Even Number
An even number 
for which 
. The first few Positive doubly even numbers are 4, 8, 12, 16,... (Sloane's A008586).
References
Sloane, N. J. A. Sequence A008586in ``The On-Line Version of the Encyclopedia of Integer Sequences.''http://www.research.att.com/~njas/sequences/eisonline.html.
- Unitary Multiperfect Number
- Unitary Multiplicative Character
- Unitary Perfect Number
- Unitary Sociable Numbers
- Unitary Transformation
- Unitary Unimodular Group
- Unit Circle
- Unit Disk
- Unit Fraction
- Unit Matrix
- Unit Point
- Unit Ring
- Unit Sphere
- Unit Square
- Unit Step
- Unit Vector
- Unity
- Univalent Function
- Univariate Function
- Univariate Polynomial
- Universal Graph
- Universal Statement
- Universal Turing Machine
- Unknot
- Unknotting Number