The t-pebbling number of squares of cycles

Let c be a configuration of pebbles on a graph g. a pebbling move (step) consists of removing two pebbles from one vertex,throwing one pebble away,and moving the other pebble to an adjacent vertex. the t-pebbling number,ft(g),of a connected graph g,is the smallest positive integer such that from every configuration of ft(g) pebbles,t pebbles can be moved to any specified target vertex by a sequence of pebbling moves. in this paper,we determine the t-pebbling number for squares of cycles.