  We classify reflexive graded right ideals, up to isomorphism and shift, of
generic cubic three dimensional Artin-Schelter regular algebras. We also
determine the possible Hilbert functions of these ideals. These results are
obtained by using similar methods as for quadratic Artin-Schelter algebras. In
particular our results apply to the enveloping algebra of the Heisenberg-Lie
algebra from which we deduce a classification of right ideals of an invariant
ring of the first Weyl algebra.
