Carmichael's Totient Function Conjecture
It is thought that the Totient Valence Function 
(i.e., the Totient Valence Function nevertakes the value 1). This assertion is called Carmichael's totient function conjecture and is equivalent to the statement thatthere exists an 
such that 
(Ribenboim 1996, pp. 39-40). Any counterexample to the conjecture musthave more than 10,000 Digits (Conway and Guy 1996). Recently, the conjecture was reportedly proven byF. Saidak in November, 1997 with a proof short enough to fit on a postcard.
References
Conway, J. H. and Guy, R. K. The Book of Numbers. New York: Springer-Verlag, p. 155, 1996. Ribenboim, P. The New Book of Prime Number Records. New York: Springer-Verlag, 1996.
- Square Root Inequality
- Square Root Method
- Square Triangular Number
- Square Wave
- Squaring
- Squeezing Theorem
- s-Run
- S-Signature
- SSS Theorem
- Stability
- Stability Matrix
- Stabilization
- Stable Equivalence
- Stable Improper Node
- Stable Node
- Stable Spiral Point
- Stable Star
- Stable Type
- Stack
- Stamp Folding
- Standard Deviation
- Standard Error
- Standardized Moment
- Standardized Score
- Standard Map