r generate time series with seasonality r how to get seasonality how does arima model generate r how to model a time series how to generate trending and seasonal forecasts when you add seasonality to the formula for r do you add trend or seasonality to the forecast how are r forecasts calculated how to generate a seasonal forecast in r how to use forecast for r how to make a seasonal forecast in r how do you model forecasts in r how to make r forecasts with seasonality what is an arima formula r generates trend and seasonality forecasts how to combine seasonality and trend in forecast how to make forecast in r how to do seasonality and trend for r do i need to use the forecast when importing a seasonarily how to get seasonal seasonality in r what does arima forecaster do?