If you get the infinite summation portfolio, chances are that you might be spending a good handful of minutes adding up your terms on your calculator and showing the calculations. However, there is a function to automatically sum up the list of terms with a respective sequence. NOTE: You must have TI-software, your TI calculator and your link cable in order to get screenshots.
First of all you can you the sum and sequence function to calculate your finite sum of terms.
sum(seq(expression,variable,beginning term (usually 0),ending term[,increment]))
There is also a method of producing a summation graph instead of a function graph, which will be shown in the images I've attached. First you must set your calculator to sequential mode. Then on the "y=" button, you will get something completely different. Insert your summation function on u(n), and just copy the rest as it serves as the expression needed for the function to sum. In the summation graph, the term function is also shown so you might want to use editing software to rid the points. Also, from the charts, u(n) is the term value while v(n) is the sum value.
Some functions are ones that I am not wholly familiar with. I was searching how to do this online, and got most of my information came from this site: http://www2.stetson.edu/~mhale/teach/ti84.htm
If there are any questions, don't hesistate to contact me.