In this tutorial you are shown what an arithmetic progression (A.P.) is and the formulae used to find the n^{th} term and the sum S_{n} of the first n terms in the sequence with a simple example.

#### Example in the video

- An arithmetic sequence has the terms 5, 9, 13, 17, …

Find the 21st term and the sum of the first 21 terms, S_{21}.