  In four-dimensional conformal field theory, the numbers a and c are defined
as coefficients of particular terms in the operator product expansion (OPE) of
the energy-momentum tensor. With supersymmetry there are relations between
these coefficients and mixed R-symmetry and gravitational anomalies. In this
paper we prove a relationship between these coefficients and anomalies to
holomorphic reparametrization symmetry at the level of the holomorphic twist.
