\[\nabla^{4}u_{0,0}=\frac{1}{6h^{4}}\,(184u_{0,0}-(u_{0,3}+u_{0,-3}+u_{3,0}+u_{-%
3,0})+14(u_{0,2}+u_{0,-2}+u_{2,0}+u_{-2,0})-77(u_{0,1}+u_{0,-1}+u_{1,0}+u_{-1,%
0})+20(u_{1,1}+u_{1,-1}+u_{-1,1}+u_{-1,-1})-(u_{1,2}+u_{2,1}+u_{1,-2}+u_{2,-1}%
+u_{-1,2}+u_{-2,1}+u_{-1,-2}+u_{-2,-1}))+O\left(h^{4}\right).\]