 Sometimes the Hahn class is taken to include limiting cases of these polynomials, in which case it also includes the classical orthogonal polynomials.Hahn polynomials are defined in terms of generalized hypergeometric functions by 

If formula_2, these polynomials are identical to the Discrete Chebyshev polynomials except for a scale factor.Closely related polynomials include the dual Hahn polynomials "R""n"("x";γ,δ,"N"), the continuous Hahn polynomials "p""n"("x","a","b", , ), and the continuous dual Hahn polynomials "S""n"("x";"a","b","c").