Let ϱ(n) denote the number of positive regular integers (mod n) less than or equal to n and let ϱr(n) (r ≥ 1) be the multidimensional generalization of the arithmetic function ϱ(n). We study the ...

Y. Altın, Properties of some sets of sequences defined by a modulus function, Acta Math. Sci. Ser. B Engl. Ed. 29(2) (2009), 427–434. G. Das and S. K. Mishra, Banach limits and lacunary strong almost ...