What is the easiest way to lock a cell so that the formula cannot be edited, but the worksheet is still editable.

For example, you have numbers down column A to like A200, then on A201 you have a sum function, after you do it once, you want to clear all those 200 numbers and enter different ones. It is easiest to just select column A and clear contents, but that would erase your sum function in a201. Does that make sense?