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.
- Arboricity
- Arc
- Arch
- Archimedean Solid
- Archimedean Solid Stellation
- Archimedean Spiral
- Archimedean Spiral Inverse Curve
- Archimedean Valuation
- Archimedes Algorithm
- Archimedes' Axiom
- Archimedes' Cattle Problem
- Archimedes' Circles
- Archimedes' Constant
- Archimedes' Hat-Box Theorem
- Archimedes' Lemma
- Archimedes' Midpoint Theorem
- Archimedes' Postulate
- Archimedes' Problem
- Archimedes' Recurrence Formula
- Archimedes' Spiral
- Archimedes' Spiral Inverse
- Arc Length
- Arc Minute
- Arcsecant
- Arc Second