A=1+1/2+1/3+1/4+1/5+.+1/15+1/16
=1+1/2+(1/3+1/4)+(1/5+1/6+1/7+1/8)+(1/9+...+1/15+1/16)
>1+1/2+(1/4+1/4)+(1/8+1/8+1/8+1/8)+(1/16+...+1/16+1/16)
=1+1/2+(1/4×2)+(1/8×4)+(1/16×8)
=1+1/2+1/2+1/2+1/2=3
另一方面,
A=1+1/2+1/3+1/4+1/5+.+1/15+1/16
=1+1/2+(1/3+1/4+1/5)+(1/6+1/7+1/8)+(1/9+1/10+1/11)+(1/12+1/13+1/14+1/15+1/16)