Deficient Number
Numbers which are not Perfect and for which
or equivalently
where
is the Divisor Function. Deficient numbers are sometimes called DefectiveNumbers (Singh 1997). Primes, Powers of Primes, and any divisors of aPerfect or deficient number are all deficient. The first few deficient numbers are 1, 2, 3, 4,5, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 21, 22, 23, ... (Sloane's A005100).See also Abundant Number, Least Deficient Number, Perfect Number
References
Dickson, L. E. History of the Theory of Numbers, Vol. 1: Divisibility and Primality. New York: Chelsea, pp. 3-33, 1952. Guy, R. K. Unsolved Problems in Number Theory, 2nd ed. New York: Springer-Verlag, p. 45, 1994. Singh, S. Fermat's Enigma: The Epic Quest to Solve the World's Greatest Mathematical Problem. New York: Walker, p. 11, 1997. Sloane, N. J. A. SequenceA005100/M0514in ``An On-Line Version of the Encyclopedia of Integer Sequences.''http://www.research.att.com/~njas/sequences/eisonline.html and Sloane, N. J. A. and Plouffe, S.The Encyclopedia of Integer Sequences. San Diego: Academic Press, 1995.
- Trinomial Triangle
- Triomino
- Triple
- Triple-Free Set
- Triple Jacobi Product
- Triple Point
- Triple Scalar Product
- Triplet
- Trip-Let
- Triple Vector Product
- Triplicate-Ratio Circle
- Trisected Perimeter Point
- Trisection
- Trisectrix
- Trisectrix of Catalan
- Trisectrix of Maclaurin
- Triskaidecagon
- Triskaidekaphobia
- Tritangent
- Tritangent Triangle
- Trivial
- Trivialization
- Trochoid
- Tromino
- True