You can't. That's obviously impossible. There exist an infinite number of series having a given specific term and converging to a give value.
Suppose you are given the term "[itex]a_i[/itex]", for i a specific number, and that the sum is "S". Choose "A" to be any number and write the geometric sequence that converges to [itex]S- a_i[/itex]. Then the series consisting first term A, the rest of the geometric series with "[itex]a_i[/itex]" stuck in a the ith place, has sum S.