Euler Square
A square Array made by combining 
objects of two types such that the first and second elements form LatinSquares. Euler squares are also known as Graeco-Latin Squares,Graeco-Roman Squares, or Latin-Graeco Squares. For many years,Euler squares were known to exist for 
, 4, and for every Odd except 
. Euler's Graeco-Roman SquaresConjecture maintained that there do not exist Euler squares of order 
for 
, 2, .... However, such squares werefound to exist in 1959, refuting the Conjecture.
References
Beezer, R. ``Graeco-Latin Squares.'' http://buzzard.ups.edu/squares.html. Kraitchik, M. ``Euler (Graeco-Latin) Squares.'' §7.12 in Mathematical Recreations. New York: W. W. Norton, pp. 179-182, 1942.
- Robinson Projection
- Robust Estimation
- Rodrigues Formula
- Rodrigues's Curvature Formula
- Rogers-Ramanujan Continued Fraction
- Rogers-Ramanujan Identities
- Rolle's Theorem
- Roman Coefficient
- Roman Factorial
- Roman Numeral
- Roman Surface
- Roman Symbol
- Romberg Integration
- Rook Number
- Rook Reciprocity Theorem
- Rooks Problem
- Room Square
- Root
- Root Dragging Theorem
- Rooted Tree
- Root Linear Coefficient Theorem
- Root-Mean-Square
- Root of Unity
- Root (Radical)
- Root Test