Figure 18.21.1 (See in context.)Figure 18.21.1: Askey scheme. The number of free real parameters is zero for Hermite
polynomials. It increases by one for each row ascended in the scheme,
culminating with four free real parameters for the Wilson and Racah
polynomials. (This is with the convention that the real and imaginary
parts of the parameters are counted separately in the case of the
continuous Hahn polynomials.)
