  We develop a recursive algorithm for the investigation of infinite sequences
of quasi-primary fields obtained from chiral primary operators (CPOs)
$O^I_k(x)$ and eventually their derivatives by applying operator product
expansions and singling out SO(6) representations. We show that normal products
of $O_2$ operators can be expressed in terms of projection operators on
representations of SO(20) and discuss intertwining operators for SO(6)
representations. Furthermore we derive $\mathcal{O}(\frac{1}{N^2})$ corrections
to AdS/CFT 4-point functions by graphical combinatorics and finally extract
anomalous dimensions by applying the method of conformal partial wave analysis.
We find infinite sequences of quasi-primary fields with vanishing anomalous
dimensions and interpret them as 1/2-BPS or 1/4-BPS fields.
