Linear sequences - investigation - spreadsheet

A very simple spreadsheet I made so that I could investigate how to find the nth term of a linear sequence. I used the idea of slightly varying an aspect of the nth term so students could see how it changed and make predictions
For example I started with 3n, then 3n+1, then 3n+2, asked them to predict 3n+3. Then predict what 3n-1 would have been.
Used it for alot more discussions such as if I double the n coefficient will the terms in the sequence double? When is this true? When is it not true?

I have shown a few examples in the spreadsheet so you know how to use it as it is not a very complex spreadsheet but it did lead to some of my best discussions about linear sequences and some of my best understanding.