您通常可以按以下方式解决此问题：
def indices(N, length=1):
"""Generate [length]-tuples of indices.
Each tuple t = (i, j, ..., [x]) satisfies the conditions
len(t) == length, 0 <= i < N and i > j > ... > [x].
Arguments:
N (int): The limit of the first index in each tuple.
length (int, optional): The length of each tuple (defaults to 1).
Yields:
tuple: The next tuple of indices.
"""
if length == 1:
for x in range(N):
yield (x,)
else:
for x in range(1, N):
for t in indices(x, length - 1):
yield (x,) + t
正在使用：
>>> list(indices(5, 2))
[(1, 0), (2, 0), (2, 1), (3, 0), (3, 1), (3, 2), (4, 0), (4, 1), (4, 2), (4, 3)]
>>> list(indices(5, 3))
[(2, 1, 0), (3, 1, 0), (3, 2, 0), (3, 2, 1), (4, 1, 0), (4, 2, 0), (4, 2, 1), (4, 3, 0), (4, 3, 1), (4, 3, 2)]
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