ABSTRACT
The necessary conditions under which there exists a solution of Equation (E), which can be written in the following form:
yn = αn un rn
+ βn vn rn ,
are given. Here (un) and (vn) are two linearly independent solutions of the linear equation
∆(rn∆yn) = anyn+1, ( lim n→∞αn = α and limn→∞ βn = β).
