  We introduce a simplified method to model the interatomic interactions of
high entropy alloys based on a lookup table of cluster energies. These
interactions are employed in replica exchange Monte Carlo simulations with
histogram analysis to obtain thermodynamic properties across a broad
temperature range. Kikuchi's Cluster Variation Method entropy formalism and
high temperature series expansions are applied to directly calculate entropy
from statistics on short- and long-range chemical order, and we discuss the
convergence of the entropy as clusters of differing size are included.
