For the recurrence an=an−1−2an−2a_n = a_{n-1} - 2a_{n-2}an=an−1−2an−2 with a0=1,a1=2a_0 = 1, a_1 = 2a0=1,a1=2, the sequence exhibits:
All positive terms
Monotonic decrease
Oscillating signs
Convergence to zero