Generating functions for moments of the quasi-nilpotent DT-operator

Ken Dykema and Catherine Yan

We prove a recursion formula for generating functions of certain renormalizations of $*$-moments of the DT$(\delta_0,1)$-operator $T$, involving an operation $\odot$ on formal power series and a transformation $\script u$ that converts $\odot$ to usual multiplication. This recursion formula is used to prove that all of these generating functions are rational functions, and to find a few of them explicitly.