  We recall the definition and the properties of a moment sequence and recall
that all real sequences that have a finite rank of its Hankel matrix (see
definition in the sequel) satisfy a homogeneous linear equation with constant
coefficients. Then we analyze cases when a difference equation with constant
coefficients and suitably chosen initial conditions and having as an input a
positive moment sequence has a solution that is a positive moment sequence. We
give one general simple result and give many examples illustrating the theory.
The main simple result states that the roots of the odd multiplicity of the
characteristic equation must lie outside the support of the measure that
produces the moment sequence that is in the input and the initial conditions
suitably chosen.
