  We report on the measurement of the all-particle cosmic ray energy spectrum
with the IceTop air shower array in the energy range from 1.58 PeV to 1.26 EeV.
The IceTop air shower array is the surface component of the IceCube Neutrino
Observatory at the geographical South Pole. The analysis was performed using
only information from IceTop. The data used in this work were taken from June
1, 2010 to May 13, 2011. During that period the IceTop array consisted of 73
stations compared to 81 in its final configuration. The measured spectrum
exhibits a clear deviation from a single power law above the knee around 4PeV
and below 1EeV. We observe spectral hardening around 18 PeV and steepening
around 130 PeV.
