  The Schrodinger equations which are exactly solvable in terms of associated
special functions are directly related to some self-adjoint operators defined
in the theory of hypergeometric type equations. The fundamental formulae
occurring in a supersymmetric approach to these Hamiltonians are consequences
of some formulae concerning the general theory of associated special functions.
We use this connection in order to obtain a general theory of Schrodinger
equations exactly solvable in terms of associated special functions, and to
extend certain results known in the case of some particular potentials.
