left, it's natural log of one over one minus Z. On the right, it's the sum Z to the N over N or the generating function for the sequence, one, one half, one third, one fourth, and so forth. so that's integration. and we can, actually, integrate more and get more, answers, but, let's look at another thing, In that is, partial sum, if you have a genarating function and you multiply by one minus Z, then you get the generating function of the partial sums of the sequence. so the original sequence is A0, A1, and so for, partial sums there A0, plus A1, A0 plus 