Congruent subsets of infinite sets of natural numbers.
Connections between connected topological spaces on the set of positive integers
In this paper we introduce a connected topology T on the set ℕ of positive integers whose base consists of all arithmetic progressions connected in Golomb’s topology. It turns out that all arithmetic progressions which are connected in the topology T form a basis for Golomb’s topology. Further we examine connectedness of arithmetic progressions in the division topology T′ on ℕ which was defined by Rizza in 1993. Immediate consequences of these studies are results concerning local connectedness of...
Convergence of subseries of the harmonic series and asymptotic densities of sets of positive integers.
Corrigendum to the paper "On ratio sets of sets of natural numbers"
Corrigendum to Theorem 5 of the paper "Asymptotic density of A ⊂ ℕ and density of the ratio set R(A) (Acta Arith. 87 (1998), 67-78)
Counting monic irreducible polynomials in for which order of is odd
Hasse showed the existence and computed the Dirichlet density of the set of primes for which the order of is odd; it is . Here we mimic successfully Hasse’s method to compute the density of monic irreducibles in for which the order of is odd. But on the way, we are also led to a new and elementary proof of these densities. More observations are made, and averages are considered, in particular, an average of the ’s as varies through all rational primes.
Covering densities