I tried to solve below recurrence relation with unrolling technique.
$A({n})=4A(\lfloor{n/7} \rfloor)+n^2$ for $n\ge 2$
$A({n})=1$ for $0\le n\le 1$
What I have come up so far is
$A(n) = 4^kA(n/7^k)+4^k\lfloor n/7^k \rfloor ^2 ....+4\lfloor n/7 \rfloor ^2 + n^2$
But I do not understand how I should advance farther from above equation. How can I simplify above statement, and substitute the base case into the equation?