f(x)+f(1-x)=4^x/(4^x+2)+4^(1-x)/(4^(1-x)+2)=1通分可得
2s=[f(1/2002)+f(2001/2002)]+……+[f(1000/2002)+f(1002/2002)]+2f(1001/2002)
=2001 s=1000.5