虽然这个答案很好，但我还是建议以下skovorodkin的答案：

>>> def partition(number):
...     answer = set()
...     answer.add((number, ))
...     for x in range(1, number):
...         for y in partition(number - x):
...             answer.add(tuple(sorted((x, ) + y)))
...     return answer
... 
>>> partition(4)
set([(1, 3), (2, 2), (1, 1, 2), (1, 1, 1, 1), (4,)])

如果要所有排列（即（1，3）和（3，1））更改answer.add(tuple(sorted((x,)+y))为answer.add((x, )+ y)