Factorion
A factorion is an Integer which is equal to the sum of Factorials of its digits. There areexactly four such numbers:
 |  |  | (1) |
 | |  | (2) |
 | |  | (3) |
 | |  | (4) |
(Sloane's A014080; Gardner 1978, Madachy 1979, Pickover 1995). The factorion of an
-digit number cannot exceed 
digits.See also Factorial
References
Gardner, M. ``Factorial Oddities.'' Ch. 4 in Mathematical Magic Show: More Puzzles, Games, Diversions, Illusions and Other Mathematical Sleight-of-Mind from Scientific American. New York: Vintage, pp. 61 and 64, 1978. Madachy, J. S. Madachy's Mathematical Recreations. New York: Dover, p. 167, 1979. Pickover, C. A. ``The Loneliness of the Factorions.'' Ch. 22 in Keys to Infinity. New York: W. H. Freeman, pp. 169-171 and 319-320, 1995.
- Dyadic
- Dyck's Theorem
- Dye's Theorem
- Dymaxion
- Dynamical System
- Dynkin Diagram
- Dürer's Conchoid
- Dürer's Magic Square
- Dürer's Shell Curve
- e
- Ear
- Early Election Results
- Eban Number
- Eberhart's Conjecture
- Eccentric
- Eccentric Angle
- Eccentric Anomaly
- Eccentricity
- Eccentricity (Graph)
- Echidnahedron
- Eckardt Point
- Eckert IV Projection
- Eckert VI Projection
- Economized Rational Approximation
- Eddington Number