Calculating entries of unitary SL₃-friezes

In this article we consider tame SL₃-friezes that arise by specializing a cluster of Pl\"ucker variables in the coordinate ring of the Grassmannian G(3,n) to $ 1 $. We show how to calculate arbitrary entries of such friezes from the cluster in question. Let F be such a cluster. We study the set Fₓ of cluster variables in F that share a given index x and derive a structure Theorem for Fₓ. These sets prove central to calculating the first and last non-trivial rows of the frieze. After that, simple recursive formulas can be used to calculate all remaining entries.