Plug in 1, 2, 3, ... up to 8 into our sequence an.
You really just need to plug in 8, but plug in lower numbers to see the sequence emerge.
For example:
a1 means n equals 1, so a1 = 25 - (3 * 1) = 25 - 3 = 22
a2 means n equals 2, so a2 = 25 - (3 * 2) = 25 - 6 = 19
...
a8 means n equals 8, so a8 = 25 - (3 * 8) = 25 - 24 = 1
I hope this helps you understand the problem.
EDIT: You can also graph your iterative rule an on a graph. The values on the x axis correspond to the value of n and the y-axis would then correspond to the value of the sequence. Notice that a8 = 1, as shown in the attached picture.
