  In this work, we propose indirect evaluation methods to check the accuracy
and the uncertainty of ab initio calculated virial coefficients. To this end,
we have used single-pressure refractive-index gas thermometry (SPRIGT) to
estimate the impact of the second density virial coefficient B of helium-4 on
temperature measurements between 5 K to 25 K. Our results, in good agreement
with values of B obtained from recent ab initio calculations by Czachorowski et
al. [Phys. Rev. A 102, 042810 (2020)], suggest uncertainties u(B) estimated
previously by other authors were too conservative. Concerning the value of the
third density virial coefficient C of helium-4, calculated ab initio by
Garberoglio et al. [J. Chem. Phys. 134, 134106 (2011)], our results suggest
their uncertainty u(C) is between 1.5 and 10.2 times too high.
