LECTURE NOTES IN ANALYSIS (2011)
《LECTURE NOTES IN ANALYSIS (2011)》 · 第 446 页 · Section 10.1「Partitions」，Definition 10.1
The partition function $p(n)$ is defined as the number of ways that the positive integer $n$ can be written as a sum of positive integers. Although the parts need not be distinct, two partitions are not considered as different if they differ only in the order of their parts.