How can I get an actual equation for an ARIMA model? For example, I have an ARIMA (2,1,2)x(2,0,1)12 periods/season and need the actual equation?
You can save the the Prediction Formula for the model and you'll get a new data table with a formula column.
Unfortunately, Time Series models don't have simple formulas and the prediction column uses the ARIMA Forecast() function to do it's real work.
How do you want to use the prediction model?