Tetranacci Number
The tetranacci numbers are a generalization of the Fibonacci Numbers defined by 
, 
,
, 
, and the Recurrence Relation
for
. They represent the 
case of the Fibonacci n-Step Number. Thefirst few terms are 1, 1, 2, 4, 8, 15, 29, 56, 108, 208, ... (Sloane's A000078). The ratio of adjacent terms tends to1.92756, which is the Real Root of 
. See also Fibonacci n-Step Number, Fibonacci Number, Tribonacci Number
References
Sloane, N. J. A. SequenceA000078/M1108in ``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.
- Annihilator
- Annulus
- Annulus Conjecture
- Annulus Theorem
- Anomalous Cancellation
- Anomalous Number
- Anonymous
- Anosov Automorphism
- Anosov Diffeomorphism
- Anosov Flow
- Anosov Map
- ANOVA
- Anthropomorphic Polygon
- Anthyphairetic Ratio
- Antiautomorphism
- Anticevian Triangle
- Antichain
- Anticlastic
- Anticommutative
- Anticommutator
- Anticomplementary Triangle
- Antiderivative
- Antidifferentiation
- Antigonal Points
- Antihomography