The sequence is alternatively defined by the recursive relation...
(1)
The procedure for solving (1) has been described a lot of times, the last in...
http://www.mathhelpforum.com/math-he...ce-176658.html
Following the procedure you find that...
a) if the sequence converges to -1
b) if the sequence converges to 2
c) if the sequence diverges...
Kind regards