    int a = 0;    for (int i = 0; i < n*n; ++i) {        for (int j = 0; j <= i; ++j) {            a += j;        }    }Could someone help prove to me that this is function is $O(N^4)$. I remember doing this problem a while back, but now I do not see it.I understand that the outer loop is $O(N^2)$ but I am unsure of how this would cause the inner loop to be $O(N^2)$ as well
Big O Unsure (single problem)
asymptotics