$U_m\left(\xi \right)\sim D_m\left(\xi \right)-\frac{1}{2^{6}h}\left(D_{m+4}\right(\xi )-4!\mathrm{dbinom}m4D_{m-4}(\xi \left)\right)+\frac{1}{2^{13}{h}^2}\left(D_{m+8}\right(\xi )-2^5(m+2)D_{m+4}(\xi )+4!2^5(m-1)\mathrm{dbinom}m4D_{m-4}(\xi )+8!\frac{m}{8}{D}_{m-8}(\xi \left)\right)+\cdots$