and, in particular, is symmetric in r, s, t. A closed formula has been obtained for Cry by Watson [41. We begin by obtaining the same formula by a very simple argument. In ? wce (lerive a simple recurrence relation suitable for rapidly generating the coefficients as needed when working with a high speed computing machine. This will be seen to be more useful in practice than the formal expression in equation (7). 2. It is known [1t that the Laplace transform of L,(x) is p"'(p 1) while that of Lh(x)Lk(X) is