My BC students are just beginning Power Series .. and I have to say how much fun is to teach the concept with the Foerster text. I used to sort of dread this relatively difficult concept .. I'm not sure I ever really understood it completely before I started using this text. I love the way it is approached. We also use the "Explorations" text - Advanced Placement Calculus with the TI-89 (Chapter 9 Infinite Sequences and Series) from Texas Instruments for very concise instructions on how to calculate and graph the problems.