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Congruences for powers of the partition function

Number Theory 2022-06-22 v1

Abstract

Let pt(n)p_{-t}(n) denote the number of partitions of nn into tt colors. In analogy with Ramanujan's work on the partition function, Lin recently proved in \cite{Lin} that p3(11n+7)0(mod11)p_{-3}(11n+7)\equiv0\pmod{11} for every integer nn. Such congruences, those of the form pt(n+a)0(mod)p_{-t}(\ell n + a) \equiv 0 \pmod {\ell}, were previously studied by Kiming and Olsson. If 5\ell \geq 5 is prime and t∉{1,3}-t \not \in \{\ell - 1, \ell -3\}, then such congruences satisfy 24at(mod)24a \equiv -t \pmod {\ell}. Inspired by Lin's example, we obtain natural infinite families of such congruences. If 2(mod3)\ell\equiv2\pmod{3} (resp. 3(mod4)\ell\equiv3\pmod{4} and 11(mod12)\ell\equiv11\pmod{12}) is prime and r{4,8,14}r\in\{4,8,14\} (resp. r{6,10}r\in\{6,10\} and r=26r=26), then for t=srt=\ell s-r, where s0s\geq0, we have that \begin{equation*} p_{-t}\left(\ell n+\frac{r(\ell^2-1)}{24}-\ell\Big\lfloor\frac{r(\ell^2-1)}{24\ell}\Big\rfloor\right)\equiv0\pmod{\ell}. \end{equation*} Moreover, we exhibit infinite families where such congruences cannot hold.

Keywords

Cite

@article{arxiv.1604.07495,
  title  = {Congruences for powers of the partition function},
  author = {Madeline Locus and Ian Wagner},
  journal= {arXiv preprint arXiv:1604.07495},
  year   = {2022}
}
R2 v1 2026-06-22T13:40:44.879Z