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Relations among arithmetical functions, automatic sequences, and sum of digits functions induced by certain Gray codes

Yuichi Kamiya, Leo Murata (2012)

Journal de Théorie des Nombres de Bordeaux

In the study of the 2 -adic sum of digits function S 2 ( n ) , the arithmetical function u ( 0 ) = 0 and u ( n ) = ( - 1 ) n - 1 for n 1 plays a very important role. In this paper, we firstly generalize the relation between S 2 ( n ) and u ( n ) to a bijective relation between arithmetical functions. And as an application, we investigate some aspects of the sum of digits functions S 𝒢 ( n ) induced by binary infinite Gray codes 𝒢 . We can show that the difference of the sum of digits function, S 𝒢 ( n ) - S 𝒢 ( n - 1 ) , is realized by an automaton. And the summation formula of the sum...

Remarks on Ramanujan's inequality concerning the prime counting function

Mehdi Hassani (2021)

Communications in Mathematics

In this paper we investigate Ramanujan’s inequality concerning the prime counting function, asserting that π ( x ) 2 < e x log x π x e for x sufficiently large. First, we study its sharpness by giving full asymptotic expansions of its left and right hand sides expressions. Then, we discuss the structure of Ramanujan’s inequality, by replacing the factor x log x on its right hand side by the factor x log x - h for a given h , and by replacing the numerical factor e by a given positive α . Finally, we introduce and study inequalities analogous...

Remarks on Steinhaus’ property and ratio sets of sets of positive integers

Tibor Šalát (2000)

Czechoslovak Mathematical Journal

This paper is closely related to an earlier paper of the author and W. Narkiewicz (cf. [7]) and to some papers concerning ratio sets of positive integers (cf. [4], [5], [12], [13], [14]). The paper contains some new results completing results of the mentioned papers. Among other things a characterization of the Steinhaus property of sets of positive integers is given here by using the concept of ratio sets of positive integers.

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