It's a plot of the following:
Let $$f_{(n)} = \frac{np_n}{(p_1 + \ldots + p_n)}$$ so that $$g_{(n)} = \left|\space f_{(n)} - f_{(n-k)}\right| $$ where $n > k$ and $k = 5$ in this example.
For each $k$ the graph shows this 'hammock'-like pattern and it seems that the bigger the number is for $k$, the more the hammock unravels. I've never seen this kind of graph before and wondered if anyone recognizes it from some other function.