answered 6 years ago
What about :
sage: var("q") q sage: f(q)=(q+1)/(q-3);f q |--> (q + 1)/(q - 3) sage: f.maxima_methods().powerseries(q,oo) 4*sum(3^(i1 - 1)/q^i1, i1, 0, +Infinity) - 1/3