  Using schematic model potentials, we calculate exactly the virial
coefficients of a classical gas up to sixth order and use them to assess the
convergence properties of the virial expansion of basic thermodynamic
quantities such as pressure, density, and compressibility. At sufficiently
strong couplings, as expected, the virial expansion fails to converge. However,
at least for the interactions and parameter ranges we explored, we find that
Pad\'e-Borel resummation methods are extremely effective in improving the
convergence of the expansion.
