The ornamental design for a tablebase, as shown and described.
FIG. 1 is a perspective view of a table base comprising the new design;
FIG. 2 is a top view thereof;
FIG. 3 is a right side view thereof, where the left side view is a mirror image thereof;
FIG. 4. is a front view thereof, where the back side view is a mirror image thereof; and,
FIG. 5 is a right side view of an alternative embodiment of said new design, portions of which are cut away to illustrate indeterminate length, which is the sole difference between it and FIGS. 1–4.
The broken lines in the figures are for illustrative purposes only and form no part of the claimed invention.