On the covariances of outdegrees in random plane recursive trees

In 2005 Janson, extending earlier work of Mahmoud, Smythe, and Szyma'nski, established the joint asymptotic normality of the outdegrees of a random plane recursive tree. In particular, he gave an explicit description of the limiting covariance matrix. Our aim here is to provide substantially simplified expression for the limiting covariance matrix.