Universality of the Einstein equations for Ricci squared Lagrangians

It has been shown recently that, in the first-order (Palatini) formalism, there is universality of the Einstein equations and the Komar energy-momentum complex, in the sense that for a generic nonlinear Lagrangian depending only on the scalar curvature of a metric and a torsionless connection one always gets the Einstein equations and Komar's expression for the energy-momentum complex. In this paper a similar analysis (also within the framework of the first-order formalism) is performed for all nonlinear Lagrangians depending on the (symmetrized) Ricci square invariant. The main result is that the universality of the Einstein equations and Komar's energy-momentum complex also extends to this case (module a conformal transformation of the metric).