Sequences

Press Y= to enter the equation editor. Enter the sequence, u(n)=1/(n^2+1), then press . Notice that the graph style icon to the left of u(n)= consists of three dots in a diagonal line, indicating that the graph style is in dot mode. Press to access the zoom menu, then select 6:ZStandard to view a graph. The graph in the standard viewing window displayed in the middle screen below is unsatisfactory. For a better view, press to access the window menu. The graph below at right uses the window settings Xmin = 0, Xmax = 10, Xscl = 1, Ymin = 0, Ymax = .6, Yscl = .1. Then press to view a plot of the sequential points.

In the latter part of a calculus course, one begins to work with sequences and series. A sequence is simply a function whose domain is limited to integers rather than real numbers. We illustrate with the sequence .

To work with sequences, first we need to set the function mode to sequence. Press to access the mode menu. In the fourth line of the mode menu (the Func line), highlight Seq and then press . We also recommend setting the graph style to Dot (highlight Dot and press ).

One may work with sequences now just like with functions. You may obtain a sequential value or a table of values. For example, press to return to the home screen. Press TBLSET to access the table setup screen. Set up the table as indicated in the screen below at left. To view the table, press . For example, note that u5 .038436

Warning Remember to set the graph mode back to function (Func) for doing usual calculator work.