Ruler Function
The exponent of the largest Power of 2 which Divides a given number 
. The values of the rulerfunction for 
, 2, ..., are 1, 2, 1, 3, 1, 2, 1, 4, 1, 2, ... (Sloane's A001511).
References
Guy, R. K. ``Cycles and Sequences Containing All Permutations as Subsequences.'' §E22 in Unsolved Problems in Number Theory, 2nd ed. New York: Springer-Verlag, p. 224, 1994. Sloane, N. J. A. SequenceA001511/M0127in ``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.
- Additive Persistence
- Adem Relations
- Adequate Knot
- Adiabatic Invariant
- Adjacency Matrix
- Adjacency Relation
- Adjacent Fraction
- Adjacent Value
- Adjacent Vertices
- Adjoint Curve
- Adjoint Matrix
- Adjoint Operator
- Adjugate Matrix
- Adjunction
- Adleman-Pomerance-Rumely Primality Test
- Adleman-Rumely Primality Test
- Admissible
- Adéle
- Adéle Group
- Affine Complex Plane
- Affine Connection
- Affine Equation
- Affine Geometry
- Affine Group
- Affine Hull