A series is the value (sum) obtained when all the terms of a sequence are added up. For example, "1, 2, 3, 4" is a sequence, with terms "1", "2", "3", and "4"; the corresponding series is the sum "1 + 2 + 3 + 4", and the value of the series is 10.
A sequence, aka progression, is an ordered list of numbers. The numbers in this ordered list are called "elements" or "terms".
While some sequences are simply random values, other sequences have a definite pattern that is used to arrive at the sequence's terms. Two such sequences are the arithmetic and geometric sequences.
An arithmetic sequence is one that has a sequence of values follows a pattern of adding a fixed or constant amount from one term to the next.
vCalc's Series and Sequence contains equations that compute the sum of the terms of a sequence.