The ornamental design for a keyboard for tabletcomputer, as shown and described.
1. Keyboard for tablet computer
1.1 : Perspective
1.2 : Rear perspective view
1.3 : Top
1.4 : Bottom
1.5 : Right
1.6 : Left
1.7 : Back
1.8 : Front
1.9 : Referential rear perspective view
The feature of the claimed design resides in the shape and configuration of the rear part of the keyboard, being equipped with a pen holder; the pen holder can house a pen in either of a rightward or leftward direction; the broken lines shown in the drawings illustrate portions of the keyboard that form no part of the claimed design.