Quote (MsRailgun @ Oct 5 2013 07:16pm)
A(b) = A(b/2) + A(b/4) for b is an even power of 4 > 0
A(1) = 1.
Paying well for explanation.
It's not 'recurrence'. The phrase you want is mathematical induction.
To prove something by mathematical induction, you need to first prove the "base case", meaning the very lowest number that fits the definition given in your problem. What I can't understand, though, is what you mean by "b is an even power of 4 > 0".
The second step is to first assume that you have some arbitrary (and valid) value for b that the equation works for. Assume A(k) == A(k/2) + A(k/4). Now from there, prove that the equation is also true for A("k+1"). I said k+1, but in reality that depends on how you're defining your allowed b values. If it's even powers of 4, then assume A(k) and prove A(16k) is also true. It's whatever the next highest allowed value for b is. For even powers of 4, that means you would have to multiple by 4^2 to get to the next even power of 4.