Genus Theorem
A Diophantine Equation
can be solved for
a Prime Iff 
or 
. The representation is unique except for changes ofsign or rearrangements of 
and 
.See also Composition Theorem, Fermat's Theorem- Sieve of Eratosthenes
- Sievert Integral
- Sievert's Surface
- Sifting Property
- Sigma Algebra
- Sigma Function
- Sigmoid Curve
- Sigmoid Function
- Sign
- Signalizer Functor Theorem
- Signature (Knot)
- Signature (Quadratic Form)
- Signature (Recurrence Relation)
- Signature Sequence
- Signed Deviation
- Significance
- Significance Test
- Significant Digits
- Significant Figures
- Signpost
- Signum
- Silver Constant
- Silverman Constant
- Silverman's Sequence
- Silver Mean