Specific number of cell to fill with color based in a dynamic cell range:

Example to SUM:
If cell D10 have the value 5 SUM from A10 to A15.
If the number from cell D10 changes to 7 and SUM changes from A10 to A17.

Thanks to "Ron Coderre":
=SUM(A10:INDEX(A10:A20,D10))
But now,i was wondering... its possible to fill the cells with color?
Example:
If D10 have the value "2" then the cell A10 to A12 will be filled also with color.

I´ve tried to use the Conditional Formation with formula but i couldn't do it.
Can i use "INDEX" in the conditional formating?

If the value from the cell D10 changes the number of cells that will be filled with color will change also.

Thank you.