“…Since then, the theory provided many interesting and nice results, for example [1], [2], [3], [16], [18], [19] and [26], just to mention some. Concerning p n -sequences of semigroups and related topics, we have [12], [11], [8], then the characterization of semigroups having sub-exponential (also called log-linear) p n -sequences [9] (which is going to be utilized in the sequel), and also [5], [6], [7], [10] and many others.…”