Introduced soon after ordinary hypergeometric functions, the

functions have long been studied as theoretical generalizations of hypergeometric and other functions.
Mathematica for the first time allows full numerical evaluation of

functions, as well as extensive symbolic manipulation—allowing routine use of

functions in closed forms for sums, products, recurrence equation solutions, and more.
Sum,
Product — compute sums and products involving

functions
RSolve — solve

-recurrence relations