A series is the indicated sum of the terms of a sequence.
Finite sequence :
Related finite series :
Infinite sequence :
Related infinite series :
A series can be written in an abbreviated form by using the Greek letter (sigma), called the summation sign. For instance, to abbreviate the writing of the series first notice that the general term of the series is . The series begins with the term for and ends with the term for . Using sigma notation, you can write this series as , which is read “the sum of for values of from to .”