f(log下2上3)=f(x+1)=f(log2(3)+1)
= f(log2(3)+log2(2))
=f(log2(6))
显然log2(6)小于4
所以f(log2(6))=f(log2(6)+1)=f(log2(6)+log2(2))=f(log2(12))
显然log2(12)小于4=log2(16)
所以f(log2(12))=f(log2(12)+1)=f(log2(12)+log2(2))=f(log2(24))
此时,log2(24)大于4了
则f(log2(24))=(1/2)^log2(24)=[2^-1]log2(24)=[2^log2(24)]^-1=24^-1=1/24
log2(3)<4
f(log2(3))
=f(log2(3)+1)
=f(log2(3)+log2(2))
=f(log2(6))
=f(log2(6)+1)
=f(log2(12))
=f(log2(12)+1)
=f(log2(24))
=(1/2)^log2(24)=1/(2^log2(24))=1/24