macOS Grapher recursive function
I was looking for this myself and was a bit disappointed at the dismissive comments under your question. Fortunately, it is quite simple: Choose “Equation > New Equation from Template… > Other > Series”.

Edit: The best resource on Grapher I know is this PDF. It is a bit hard to read at times because it has so much content, but it is an invaluable resource if you want to make full use of Grapher. You can find recursive functions under “Sequences”.