  Starobinsky inflation is an attractive, fundamental model to explain the
Planck measurements, and its higher-order extension may allow us to probe
quantum gravity effects. We show that future CMB data combined with the 21cm
intensity map from SKA will meaningfully probe such an extended Starobinsky
model. A combined analysis will provide a precise measurement and intriguing
insight into inflationary dynamics, even accounting for correlations with
astrophysical parameters.
