Inflation and dark energy from f(R) gravity
  The standard Starobinsky inflation has been extended to the $R + \alpha R^n - \beta R^{2-n}$ model to obtain a stable minimum of the Einstein frame scalar potential of the auxiliary field. As a result we have obtained obtain a scalar potential with non-zero value of residual vacuum energy, which may be a source of Dark Energy. Our results can be easily consistent with PLANCK or BICEP2 data for appropriate choices of the value of $n$. 
Michal Artymowski and Zygmunt Lalak
hep-th gr-qc