For univariate or single independent variable regressions, this formula can be used (details here):
$$R^2_{adjusted} = 1- \dfrac{SSRes}{SSTotal}\dfrac{n-1}{n-p}$$
However, I cannot find a similar formula for multivariate or multiple independent variable regressions (but I did find that the number of degrees of freedom in a multiple regression equals n-k-1, where k is the number of variables).