=1/4[4/1×5+4/5×9+4/9×13+4/13×17+……+4/2009×2013]
=1/4×(1-1/5+1/5-1/9+1/9-1/13+1/13-1/17+……+1/2009-1/2013]
=1/4×(1-1/2013)
=503/2013