“…also known as the discrete time birth-and-death process, where the state space can be interpreted as the size of a certain population (for more details see [13]). It is interesting to remark that many problems of the real world can be modeled by birth-and-death processes: frequently cited examples include problems in evolutionary biology, ecology, population genetics, epidemiology and queuing theory (see [2,7,15] and references therein). The most simple example of this class can be defined as follows: the transition probability from the state j to the state i is given by p ij where p ii = δ i , p i+1,i = b i and p i,i+1 = c i+1 (where i ∈ {0, 1, .…”