On a pair of difference equations for the $_4F_3$ type orthogonal   polynomials and related exactly-solvable quantum systems
  We introduce a pair of novel difference equations, whose solutions are expressed in terms of Racah or Wilson polynomials depending on the nature of the finite-difference step. A number of special cases and limit relations are also examined, which allow to introduce similar difference equations for the orthogonal polynomials of the $ _3 F_2$ and $ _2 F_1$ types. It is shown that the introduced equations allow to construct new models of exactly-solvable quantum dynamical systems, such as spin chains with a nearest-neighbour interaction and fermionic quantum oscillator models. 
E.I. Jafarov, N.I. Stoilova and J. Van der Jeugt
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