Note on the reheating temperature in Starobinsky-type potentials

The relation between the reheating temperature, the number of e-folds and the spectral index is shown for the Starobinsky model and some of its descendants through a very detailed calculation of these three quantities. The conclusion is that for viable temperatures between $1$ MeV and ${10}^9$ GeV the corresponding values of the spectral index enter perfectly in its $2sigma$ C.L., which shows the viability of this kind of models.