f(1)=af(2)=xf(3)=x-1f(4)=x+1f(5)=-xx(6)=af(1+5)=f(1)周期为5f(1)+f(2)+f(3)+f(4)+f(5) = a+x+x-1+x+1-3x = af(1)+f(2)+f(3)+f(4)+f(5)+ ......f(2010)= (2010/5)*{f(1)+f(2)+f(3)+f(4)+f(5)}= 402a
