30*(1/15+1/35+1/63+1/99+1/143+1/195)=

30*(1/15+1/35+1/63+1/99+1/143+1/195)=
30*(1/15+1/35+1/63+1/99+1/143+1/195)=

30*(1/15+1/35+1/63+1/99+1/143+1/195)=
1/15=1/3-1/5;1/35=1/5-1/7;同理可得～最后一项是1／13－1／15～30＊（1／3．．．．．．．．．－1／15）＝8／15