Analytical solutions in $R+qR^{n}$ cosmology from singularity analysis
  The integrability of higher-order theories of gravity is of importance in the determining the properties of these models and so their viability as models of reality. An important tool in the establishment of integrability is the singularity analysis. We apply this analysis to the case of fourth-order theory of gravity $f(R) = R + qR^{n}$ to establish those values of the free parameters $q$ and $n$ for which integrability in this sense exists. As a prelininary we examine the well-known case of $n = 4/3$. 
Andronikos Paliathanasis and P.G.L. Leach
gr-qc math-ph math.MP