Now, we need to examine the values of τ n-1,vi for i ∈ . They can be obtained using the above onestep analysis, but now considering the chain in reverse; since they form part of the two end squares of the polyomino chain at time n -1. Referring to this, Table provides the corresponding values of τ n-1,vi in each entry, i.e, the entry in the n-th row and i-th column, give us the number of all the vertices in P C n-1 situated at a distance of two from v i , where v i is one of the last six vertices of the P C n-1 . Therefore, for n ≥ 5