Universal recursive formula for GJMS-operators in the locally conformally flat case

Let $(M,g)$ be a locally conformally flat Riemannian manifold of dimension $n\geq3$. For $N\geq1$, let ${\mathcal M}_{2N}$ denote the operator defined from the recursive construction, let $[\cdot]^0$ denote the non-constant part, let ${\sf P}$ be the Schouten tensor, and let $\delta$ be the negative divergence. Universal recursive formula.

$${\mathcal M}_{2N}^0=-c_N\delta({\sf P}^{N-1}\#d),\qquad c_N=2^{N-1}N!(N-1)!.$$

This conjecture seeks a recursive description of all subcritical GJMS-operators in the locally conformally flat category. The formula is established in the first few orders, but is not known in general.