Sum of Products
A partition of $n$ is a set of positive integers for which the sum equals $n$. The partitions of 5 are: $\{5\},\{1,4\},\{2,3\},\{1,1,3\},\{1,2,2\},\{1,1,1,2\}$ and $\{1,1,1,1,1\}$. Further we define...