Series - The Basics
That topic is infinite series. So just define what is an infinite series? Well, let's start with a sequence {a_{n}}^{∞}_{n=1} (note the n=1 is for convenience, it can be anything) and describe the following,
The s_{n} are called partial sums and notice that they will form a sequence, {s_{n}}^{∞}_{n=1}. Also recall that the ∑ is used to present this summation and termed as a variety of names. The most general names are:
a. Series notation,
b. Summation notation, and
c. Sigma notation.