So the question is A0 = 4, A(n)=A(n-1) - n 
So far what I have is A(1)=3, A(2)=1, A(3)=-2, A(4)=-6.
I understand how to get those numbers and I could infinitely go up if I wanted to. But I'm having a hard time understanding the logic to finding the solution.

Thanks guys!