Fractran
Fractran is an algorithm applied to a given list 
, 
, ..., 
of Fractions. Given a startingInteger 
, the Fractran algorithm proceeds by repeatedly multiplying the integer at a given stage by thefirst element 
given an integer Product. The algorithm terminates when there is no such .
The list
with starting integer
generates a sequence 2, 15, 825, 725, 1925, 2275, 425, 390, 330, 290, 770, ... (Sloane's A007542). Conway (1987)showed that the only other powers of 2 which occur are those with Prime exponent: 
, 
, 
, 
, ....
References
Conway, J. H. ``Unpredictable Iterations.'' In Proc. Number Theory Conf., Boulder, CO, pp. 49-52, 1972. Conway, J. H. ``Fractran: A Simple Universal Programming Language for Arithmetic.'' Ch. 2 in Open Problems in Communication and Computation (Ed. T. M. Cover and B. Gopinath). New York: Springer-Verlag, pp. 4-26, 1987. Sloane, N. J. A. SequenceA007542/M2084in ``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.
- Hypergeometric Function
- Hypergeometric Identity
- Hypergeometric Polynomial
- Hypergeometric Series
- Hypergroup
- Hypermatrix
- Hyperparallel
- Hyperperfect Number
- Hyperplane
- Hyperreal Number
- Hyperspace
- Hypersphere
- Hypersphere Packing
- Hypervolume
- Hypocycloid
- Hypocycloid--3-Cusped
- Hypocycloid--4-Cusped
- Hypocycloid Evolute
- Hypocycloid Involute
- Hypocycloid Pedal Curve
- Hypoellipse
- Hypotenuse
- Hypothesis
- Hypothesis Testing
- Hypotrochoid