The equation of state of a gas can be expressed in terms of the series
$$
p V=n R T \sum_{i=0}^{\infty} B_{i}(T)\left(\frac{n}{V}\right)^{i}
$$
where the $B_{i}$ are called virial coefficients. Find the first three coefficients for
(i) the van der Waals equation, $\left(p+\frac{n^{2} a}{V^{2}}\right)(V-n b)=n R T$
(ii) the Dieterici equation, $p(V-n b)=n R T e^{-a n / R T V}$