Sequence

A sequence is an ordered list of things. These things are most commonly numbers, but can also be characters (for strings), or anything else you can think of.

In math, sequences are typically denoted by $$\{a_i\} = a_0, a_1, \ldots$$, where $$i$$ ranges from 0 to the upper limit. Sequences can be either finite or infinite, and therefore the upper limit may be either some non-negative integer or positive infinity.