Superperfect Number
A number 
such that
where
is the Divisor Function. Even superperfect numbers are just 
, where 
is aMersenne Prime. If any Odd superperfect numbers exist, they are Square Numbers and either or is Divisible by at least three distinct Primes.More generally, an 
-superperfect number is a number for which 
. For 
, there are no Even-superperfect numbers.
References
Guy, R. K. ``Superperfect Numbers.'' §B9 in Unsolved Problems in Number Theory, 2nd ed. New York: Springer-Verlag, pp. 65-66, 1994. Kanold, H.-J. ``Über `Super Perfect Numbers.''' Elem. Math. 24, 61-62, 1969. Lord, G. ``Even Perfect and Superperfect Numbers.'' Elem. Math. 30, 87-88, 1975. Suryanarayana, D. ``Super Perfect Numbers.'' Elem. Math. 20, 16-17, 1969. Suryanarayana, D. ``There is No Odd Super Perfect Number of the Form 
.'' Elem. Math. 24, 148-150, 1973.
- 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
- Hexlet
- HexLife
- Hex Number
- Hexomino
- Hex (Polyhex)
- Hex Pyramidal Number
- Heyting Algebra
- H-Fractal
- H-Function
- Hh Function