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Propriétés topologiques et combinatoires des échelles de numération

Guy Barat, Tomasz Downarowicz, Anzelm Iwanik, Pierre Liardet (2000)

Colloquium Mathematicae

Topological and combinatorial properties of dynamical systems called odometers and arising from number systems are investigated. First, a topological classification is obtained. Then a rooted tree describing the carries in the addition of 1 is introduced and extensively studied. It yields a description of points of discontinuity and a notion of low scale, which is helpful in producing examples of what the dynamics of an odometer can look like. Density of the orbits is also discussed.

Pseudoprime Cullen and Woodall numbers

Florian Luca, Igor E. Shparlinski (2007)

Colloquium Mathematicae

We show that if a > 1 is any fixed integer, then for a sufficiently large x>1, the nth Cullen number Cₙ = n2ⁿ +1 is a base a pseudoprime only for at most O(x log log x/log x) positive integers n ≤ x. This complements a result of E. Heppner which asserts that Cₙ is prime for at most O(x/log x) of positive integers n ≤ x. We also prove a similar result concerning the pseudoprimality to base a of the Woodall numbers given by Wₙ = n2ⁿ - 1 for all n ≥ 1.

Pseudoprvočísla

Michal Křížek, Lawrence Somer (2003)

Pokroky matematiky, fyziky a astronomie

PSL ( 2 , 7 ) septimic fields with a power basis

Melisa J. Lavallee, Blair K. Spearman, Qiduan Yang (2012)

Journal de Théorie des Nombres de Bordeaux

We give an infinite set of distinct monogenic septimic fields whose normal closure has Galois group P S L ( 2 , 7 ) .

Pure fields of degree 9 with class number prime to 3

Colin D. Walter (1980)

Annales de l'institut Fourier

The main theorem gives necessary conditions and sufficient conditions for Q ( n 9 ) to have class number prime to 3. These conditions involve only the rational prime factorization of n and congruences mod 27 of the prime factors of n . They give necessary and sufficient conditions for most n .

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