Finding a formula for the nth term of a sequence

n is the number that gives the position of each term, for example:

n = 1 for the first term
n = 3 for the third term

The aim is to make a formula so that we can find out the value of a term of a sequence just by knowing its position in that sequence.

Example video

Video: https://www.youtube.com/embed/ww2q3iRaXjA