Output of arima

Try google'ing for 'variance of an AR(1) process'.
With the same seed, if you set n=1000000, you will get something that will
compare well with what you discover from your search.

Dear All,

Here is a reprex:

set.seed(123)
b <- arima.sim(list(order = c(1,0,0),ar= .9),n=1000,sd=1)
arima(b)

Call:
arima(x = b)

Coefficients:
      intercept
         0.2250
s.e.     0.0688

sigma^2 estimated as 4.735:  log likelihood = -2196.4,  aic = 4396.81

Should sigma^2 not be equal to 1 ? Where do I misunderstand ?

Many thanks,
Ashim

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Output of arima

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