3/2+13/6+37/12+85/20+151/30+252/42+392/56
＝1+1/2+2+1/6+3+1/12+4+1/4+5+1/30+6+7
=28+(1/2+1/6+1/12+1/4+1/30)
=29+1/30
=871/30