A sequence stores a table with up to 400 columns indexed by row number. There can be at most 400 numeric columns and 200 string columns. Each of the columns has a pre-defined type: a string, integer, or floating point number.
For example, a sequence can represent a curve, either with the dependent variable x as the row number and a single value column y, or can simply store (x,y) pairs in the rows directly. Other potential applications include data logs in which the index isn't time-based. To learn more about sequences, see the concept guide.