Sets of lengths do not characterize numerical monoids.
Skolem–Mahler–Lech type theorems and Picard–Vessiot theory
We show that three problems involving linear difference equations with rational function coefficients are essentially equivalent. The first problem is the generalization of the classical Skolem–Mahler–Lech theorem to rational function coefficients. The second problem is whether or not for a given linear difference equation there exists a Picard–Vessiot extension inside the ring of sequences. The third problem is a certain special case of the dynamical Mordell–Lang conjecture. This allows us to deduce...
Solving a ± b = 2c in elements of finite sets
We show that if A and B are finite sets of real numbers, then the number of triples (a,b,c) ∈ A × B × (A ∪ B) with a + b = 2c is at most (0.15+o(1))(|A|+|B|)² as |A| + |B| → ∞. As a corollary, if A is antisymmetric (that is, A ∩ (-A) = ∅), then there are at most (0.3+o(1))|A|² triples (a,b,c) with a,b,c ∈ A and a - b = 2c. In the general case where A is not necessarily antisymmetric, we show that the number of triples (a,b,c) with a,b,c ∈ A and a - b = 2c is at most (0.5+o(1))|A|². These estimates...
Some divisibility properties of binomial coefficients and the converse of Wolstenholme's theorem.
Some extensions and refinements of a theorem of Sylvester
Some new exact van der Waerden numbers.
Some properties of a certain nonaveraging sequence.
Squares in arithmetical progressions I.
Squares in arithmetical progressions II.
Squares in products with terms in an arithmetic progression
Subset sums avoiding quadratic nonresidues
Sumsets containing long arithmetic progressions and powers of 2
Sur la fonction plus grand facteur premier
Sur la somme des puissances semblables des termes d'une progression arithmétique
The closures of arithmetic progressions in the common division topology on the set of positive integers
In this paper we characterize the closures of arithmetic progressions in the topology T on the set of positive integers with the base consisting of arithmetic progressions {an + b} such that if the prime number p is a factor of a, then it is also a factor of b. The topology T is called the common division topology.
The common division topology on
A topological space is totally Brown if for each and every nonempty open subsets of we have . Totally Brown spaces are connected. In this paper we consider a topology on the set of natural numbers. We then present properties of the topological space , some of them involve the closure of a set with respect to this topology, while others describe subsets which are either totally Brown or totally separated. Our theorems generalize results proved by P. Szczuka in 2013, 2014, 2016 and by...
The Connell sum sequence.
The divisor function on residue classes I
The resolution of the diophantine equation x(x+d)...(x+(k-1)d) = by² for fixed d
The wildcard set's size in the density Hales-Jewett theorem.