Answer:
2
Explanation:
The first term is 1.
The second term (3) is obtained by adding 2 to the first term (1).
The third term (1) is obtained by subtracting 2 from the second term (3).
The fourth term (6) is obtained by adding 5 to the third term (1).
The fifth term (1) is obtained by subtracting 5 from the fourth term (6).
The sixth term (9) is obtained by adding 8 to the fifth term (1).
The seventh term (12) is obtained by adding 3 to the sixth term (9).
The eighth term (1) is obtained by subtracting 11 from the seventh term (12).
This pattern seems to alternate between adding and subtracting consecutive positive integers.
Let's continue this pattern to find the 999th and 1000th terms:
999th term: We can see that the 998th term is obtained by subtracting 997 from the 999th term. This suggests that the 999th term is 1 - 997 = -996.
1000th term: The 999th term is obtained by adding 998 to the 1000th term. This suggests that the 1000th term is -996 + 998 = 2.
So, the 999th term is -996 and the 1000th term is 2.