Instead of using one sum for each of A and B, as they are stated thus far, and instead of letting their indices n run over the full set of natural numbers, use 2 sums for each, separating the even and odd inputs of the indices. Do this by separating n into 2n, for the evens, and into 2n-1, for the odds. This is shown for both A and B in equations 11 and 12.