  Let A be an associative complex algebra and L an invariant linear functional
on it (trace). Let i be an involutive antiautomorphism of A such that
L(i(a))=L(a) for any a in A. Then A admits a symmetric invariant bilinear form
(a, b)=L(a i(b)). For A=U(sl(2))/m, where m is any maximal ideal of U(sl(2)),
Leites and I have constructed orthogonal basis whose elements turned out to be,
essentially, Chebyshev and Hahn polynomials in one discrete variable.
  Here I take A=U(gl(3))/m for the maximal ideals m which annihilate
irreducible highest weight gl(3)-modules of particular form (generalizations of
symmetric powers of the identity representation). In this way we obtain
multivariable analogs of Hahn polynomials.
