This, but unironically. Their formula (11) involves basics (sums and products), the only nontrivial part would be the partial partitions, and for that the first

This, but unironically. Their formula (11) involves basics (sums and products), the only nontrivial part would be the partial partitions, and for that the first paragraph of chapter 2 explains how to get it from ordinary partitions, which is a standard function.