1x1 matrix addrow problem

[std]

Thank you very much for your time.
Your solution works indeed.

However, as I described on my initial post, I am writing down on paper the steps of a calculation workflow. My aim is to make a workflow as general as it can be, so that it can handle all the possible cases that I may come across at the exams (that includes both n=1 and n>1) without too much thinking. Plug and play! Really straightforward workflow without "if this" and "if that".
Up to the point so far I have made the workflow to do the job with simple formulas, without using code to make a program (there is no need for programming it). Just really basic calculations on each step, but this last step buzzes me.
What I want, is a single formula consisting of simple functions, that will work with whatever integer n (n=1 or n>1).
I don't want to use "if" statements for the formulas, as it will make it vulnerable to typing mistakes by me.
I don't want write down 2 formulas for this calculation step, one for each case (one formula for n=1 and one formula for n>1).
I want one formula that will work for both cases if this is possible.
I hope I described it better this time!