Some Possible Features of General Expressions for Lovelock Tensors and   for the Coefficients of Lovelock Lagrangians Up to the 15th Order in   Curvature (and Beyond)
  This paper presents some possible features of general expressions for Lovelock tensors and for the coefficients of Lovelock Lagrangians up to the 15th order in curvature (and beyond) in terms of the Riemann-Christoffel and Ricci curvature tensors and the Riemann curvature scalar for n-dimensional differentiable manifolds having a general linear connection. 
C. C. Briggs