University of California, San Diego: Edward Bender and S. Williamson's "Arithmetic, Logic and Numbers: Induction, Sequences, and Series"

Read Theorem 11 and example 17 on pages IS-27 through IS-30. In doing calculation involving series, we work with sums (since a series is the sum of the succeeding terms of a sequence). In working these calculations, we also encounter the product of terms, for example when determining whether a series is bounded.