Plastic Constant
The limiting ratio of the successive terms of the Padovan Sequence, 
.
References
Stewart, I. ``Tales of a Neglected Number.'' Sci. Amer. 274, 102-103, Jun. 1996.
- Sierpinski's Theorem
- Sierpinski Tetrahedron
- Sierpinski Triangle
- Sieve
- 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