Brauer Chain
A Brauer chain is an Addition Chain in which each member uses the previous member as a summand. A number 
for which a shortest chain exists which is a Brauer chain is called a Brauer Number.
References
Guy, R. K. ``Addition Chains. Brauer Chains. Hansen Chains.'' §C6 in Unsolved Problems in Number Theory, 2nd ed. New York: Springer-Verlag, pp. 111-113, 1994.
- Atiyah-Singer Index Theorem
- Atkin-Goldwasser-Kilian-Morain Certificate
- Atomic Statement
- Attraction Basin
- Attractor
- Auction
- Augend
- Augmented Amicable Pair
- Augmented Dodecahedron
- Augmented Hexagonal Prism
- Augmented Pentagonal Prism
- Augmented Polyhedron
- Augmented Sphenocorona
- Augmented Triangular Prism
- Augmented Tridiminished Icosahedron
- Augmented Truncated Cube
- Augmented Truncated Dodecahedron
- Augmented Truncated Tetrahedron
- Aureum Theorema
- Aurifeuillean Factorization
- Ausdehnungslehre
- Authalic Latitude
- Autocorrelation
- Automorphic Function
- Automorphic Number