------
## 最终结论
```python
def get_perrin(n):
    if n == 0:
        return 3
    elif n == 1:
        return 0
    elif n == 2:
        return 2
    else:
        return get_perrin(n - 2) + get_perrin(n - 3)

# Test cases
assert get_perrin(9) == 12
assert get_perrin(4) == 2
assert get_perrin(6) == 5
```