We characterize the symmetric
orthogonal polynomials {Pn(x)} such that {Pn(qnx)} is also orthogonal. This leads
to orthogonal polynomials related to the denominator polynomials of the continued
fractions of Rogers, Ramanujan, and Carlitz. We establish the orthogonality relation
for these polynomials and show that the function Σ0∞qn2zn∕(q;q)n that
appear in the aforementioned continued fractions have only real and simple
zeros.