a_2 = 1/ (1-a_1) = 1/ (1- 1/2) = 2
a_3 = 1/ (1-a_2) = 1/ (1- 2) = -1
a_4 = 1/ (1-a_3) = 1/ (1-(-1)) = 1/2 = a_1
因此.
a_4 = a_1
a_5 = a_2
a_6 = a_3
---------
a_2013 = a_2010 = a_2007 = ----= a_3 = -1
(2013= 3* 671,2010= 3*670,----)能说得清楚点吗？只需要告诉我a2013等于多少就可以了，快快快！！！十万火急啊！！！答案是-1吗a2013= -1