根据题意,不妨设f(x)=(
1
2)x
则a1=f(0)=1,
∵f(an+1)=
f(−2−an)(n∈N*),
∴an+1=an+2
∴数列{an}是以1为首项,以2为公差的等差数列
∴an=2n-1
∴a2011=4021
故选D