Write out explicitly PP5SolutionPP5 is sometimes called the

Write out explicitly P(P({5}))

Solution

P(P({5})):

is sometimes called the number of unrestricted partitions, and is implemented in the PartitionsP[n] or Number Of Partitions[n]

5=4+1

     3+1+1

2+1+1+1

   1+1+1+1+1

   partition is usually large to small.