Shift cell focus automatic

Hi,
Could some one help me,
I would like to shift focus from one cell to another automatic like -> when i type any alphanumeric key for 15 times automatic new cell will activate. i.e. if I am typing in "cell a1" for 15 times as it will touch the figure automatic the focus will move to "cell a2".

Please help.

Thank you
Anurag Agl..