  We study the density of states in graphene at high magnetic field, when the
physics is dominated by strong correlations between electrons. In particular we
use the method of Haldane pseudopotentials to focus on almost empty or almost
filled Landau levels. We find that, besides the usual Landau level peaks,
additional peaks ("sashes") appear in the spectrum. The energies of these peaks
are determined by the strength of Haldane's pseudopotentials, but as opposed to
the usual two-dimensional gas, when there is a one-to-one correspondence
between a Haldane pseudopotential and a peak in the spectrum, the energy of
each peak is determined in general by a combination of more than one
pseudopotential values. An eventual measure of these peak in the density of
states spectrum of graphene would allow one to determine the value of the
pseudopotentials in graphene, and thus test the strength of the interactions in
this system.
