suggestions on how to do this

[Terry Reedy]

"chris" <cf_1957 at hotmail.com> wrote in message 
news:xNKbe.30981$5F3.1340 at news-server.bigpond.net.au...
> I have a recursive function b(k)
>
> b(k) = -(A/k**2)*(b(k-2) - b(k-5))

This is specifically called a recurrence relation/

[snip]
> When this is expanded I get a polynomial F(A). I want to determine the
> coefficients of the polynomial so that I can find the roots of the 
> function
> F up to a specified order of A.

This is a math/numerical analysis problem.  If you don't get an answer 
here, I'd look for a text of recurrence relations and polynomials, and look 
for a math/numerical analysis newsgroup.  sci.mathematics?

Note: your subject line is so vague that a specialist who can tell you more 
could but only selectively opens threads could easily miss this.  It is 
only happenstance that I didn't.

Terry J. Reedy