Centered Square Number
A Centered Polygonal Number consisting of a central dot with four dots around it, and then additional dots in the gapsbetween adjacent dots. The general term is 
, and the first few such numbers are 1, 5, 13, 25, 41, ...(Sloane's A001844). Centered square numbers are the sum of two consecutive Square Numbers and arecongruent to 1 (mod 4). The Generating Function giving the centered square numbers is
See also Centered Pentagonal Number, Centered Polygonal Number, Centered Triangular Number, Square Number
References
Conway, J. H. and Guy, R. K. The Book of Numbers. New York: Springer-Verlag, p. 41, 1996. Sloane, N. J. A. SequenceA001844/M3826in ``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.
- Alhazen's Billiard Problem
- Alhazen's Problem
- Aliasing
- Aliquant Divisor
- Aliquot Cycle
- Aliquot Divisor
- Aliquot Sequence
- Alladi-Grinstead Constant
- Allais Paradox
- Allegory
- Allometric
- All-Poles Model
- Almost All
- Almost Alternating Knot
- Almost Alternating Link
- Almost Everywhere
- Almost Integer
- Almost Perfect Number
- Almost Prime
- Alpha
- Alphabet
- Alpha Function
- Alphamagic Square
- Alphametic
- Alpha Value