Linked from
The 12 pages that link to Partition function, each with the reason it gives.
Additive number theoryRelated: It is a central example of counting integer representations by sums.
Circle methodRelated: Hardy and Ramanujan used the method to derive an asymptotic formula for p(n).
Integer sequenceRelated: Its values count combinatorial objects indexed by integers.
q-seriesRelated: Coefficients of many q-series count integer partitions and related objects.