When does a vector stop being a vector?

I'm a MathCAD new user and am confused by what I'm seeing.  In the attached example, I've created a range variable and used it in a calculation.  The result, B, is shown and is apparently NOT a vector.

To the right, I've done the same thing except that the range variable on goes from 0 to 8.  In this case the result, D, IS a vector.  If I change the value of j to 9, the result changes in appearance and is no longer a vector.

I don't understand what's going on here which is, naturally, impairing my ability to solve a real problem.  I seem to be confused as to what constitutes a vector.