11. On a circle, there is 1 red point and 2009 blue points. Xiao Dan calculates the number of convex polygons where all vertices are blue points, while Xiao Dong calculates the number of convex polygons where one vertex is the red point. The difference between the two numbers they get is $\qquad$
11. 2017036.

For every convex $n$-sided polygon $(n \in \mathbf{N}_{+})$ calculated by Xiao Dan, there is a corresponding convex $(n+1)$-sided polygon calculated by Xiao Dong. Xiao Dong's convex $(n+1)$-sided polygon has one more red vertex than Xiao Dan's convex $n$-sided polygon. This correspondence does not hold when the polygon calculated by Xiao Dong is a triangle. Therefore, the difference in the number of polygons calculated by the two is the number of triangles calculated by Xiao Dong:
$$
\frac{2008 \times 2009}{2}=2017036 .
$$