  We calculate the perturbative value of the free energy in Lattice QCD, up to
three loops. Our calculation is performed using Wilson gluons and the
Sheikholeslami - Wolhert (clover) improved action for fermions.
  The free energy is directly related to the average plaquette. To carry out
the calculation, we compute all relevant Feynman diagrams up to 3 loops, using
a set of automated procedures in Mathematica; numerical evaluation of the
resulting loop integrals is performed on finite lattice, with subsequent
extrapolation to infinite size.
  The results are presented as a function of the fermion mass m, for any
SU(N_c) gauge group, and for an arbitrary number of fermion flavors. In order
to enable independent comparisons, we also provide the results on a per diagram
basis, for a specific mass value.
