Some convexity properties of Dirichlet series with positive terms

摘要

Some basic results for Dirichlet series ψ with positive terms via log-convexity properties are pointed out.\udApplications for Zeta, Lambda and Eta functions are considered. The concavity of the function 1/ψ is explored\udand, as a main result, it is proved that the function 1/ζ is concave on