# Impulse response of a system

I have the following difference equation: $y[n]=y[n-2]-0.25y[n-4]+x[n]-x[n-2]$ I need to find the first 6 values of the impulse response of the system characterized by that equation. When I do that, the values I get are: $[1,0,0,0,-0.25,0]$, starting from index zero. I have the answer, which states that the right response is $[1,0,0,0,-0.25,1]$. I really cannot find my mistake; any help will be appreciated.

• Your answer is correct. Why don't you program it to check your result? – Matt L. Dec 26 '14 at 12:35
• I did that, but I always get the same result (as expected). Thanks a lot! – Mojo Dec 26 '14 at 12:51