A set of numbers arranged in a prescribed order.For example, even counting numbers can be written as the infinite set {2, 4, 6, . . . }.

Each member (also called term) in a sequence can be written as an algebraic function of its position. For example, in the above even counting number sequence (2, 4, 6, . . . }, the nth term can be obtained using the general expression a_{n} = 2n.

When the sequence has a definite number of terms, it is called a finite sequence. Otherwise, it is an infinite sequence.