Generalizations of certain Carlitz’s trilinear and Srivastava–Agarwal type generating functions

In this paper, a class of trilinear generating functions for generalized Hahn polynomials is generalized. In addition, a question of Carlitz is answered and some known results are deduced as special cases. Moreover, some expansions of Srivastava–Agarwal type generating functions for Hahn polynomials are gained. Finally, additional proofs of certain Carlitz’s generating functions are given.