Friend
A friend of a number 
is another number 
such that (, ) is a Friendly Pair.
References
Anderson, C. W. and Hickerson, D. Problem 6020. ``Friendly Integers.'' Amer. Math. Monthly 84, 65-66, 1977.
- Möbius Band
- Möbius Function
- Möbius Group
- Möbius Inversion Formula
- Möbius Periodic Function
- Möbius Problem
- Möbius Shorts
- Möbius Strip
- Möbius Transformation
- Möbius Triangles
- Müller-Lyer Illusion
- Müntz Space
- Müntz's Theorem
- N
- Nabla
- Nagel Point
- Naive Set Theory
- Napierian Logarithm
- Napier's Analogies
- Napier's Bones
- Napier's Constant
- Napier's Inequality
- Napkin Ring
- Napoleon Points
- Napoleon's Problem