1/1+2+1/1+2+3+1/1+2+3+4+1/1+2+3+4+5…+1/1+2+3+4+5+…+35=1/3+1/6+1/10+1/15+...+1/630=2×(1/6+1/12+1/20+1/30+...+1/1260=2×(1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+...+1/35-1/36)=2×(1/2-1/36)=2×17/36=17/18
