数列{an}满足a1=3,a2=6,an+2=an+1-an,求a2013

问题描述:

数列{an}满足a1=3,a2=6,an+2=an+1-an,求a2013

是以3 6 3 -3 -6 -3 周期为5数列,a2013=3