1(5×7)+1(7×9)+1(9×11)+1(11×13)+1(13×15)=+S,d-f:N7w)G+Q:g:l7L*r2P'h3|.S
算式:提示1r2Y-Y(k4{:f)G+Q:g:l7L*r2P'h3|.S