Editing Sequence (section)

===Finite and infinite===
{{See also|ω-language}}
The '''length''' of a sequence is defined as the number of terms in the sequence.

A sequence of a finite length ''n'' is also called an [[n-tuple|''n''-tuple]]. Finite sequences include the '''empty sequence'''&nbsp;(&nbsp;) that has no elements.

{{anchor|Doubly infinite|Doubly-infinite sequences}}
Normally, the term ''infinite sequence'' refers to a sequence that is infinite in one direction, and finite in the other—the sequence has a first element, but no final element. Such a sequence is called a '''singly infinite sequence''' or a '''one-sided infinite sequence''' when disambiguation is necessary. In contrast, a sequence that is infinite in both directions—i.e. that has neither a first nor a final element—is called a '''bi-infinite sequence''', '''two-way infinite sequence''', or '''doubly infinite sequence'''. A function from the set '''Z''' of ''all'' [[integers]] into a set, such as for instance the sequence of all even integers ( ..., −4, −2, 0, 2, 4, 6, 8, ... ), is bi-infinite. This sequence could be denoted <math display=inline>{(2n)}_{n=-\infty}^{\infty}</math>.