设S=1+1/4+1/16+1/64+1/256+1/1024-------------------①则S/4= 1/4+1/16+1/64+1/256+1/1024+1/4096--------②①-②=3S/4=1-1/4096=4095/4096所以：S=4095/4096*4/3=1365/1024 1/18+1/54+1/108+1/180+1/270+1/378+1/...