PreprintCC BY 4.0arXiv
The two-block odd partition function
Abstract
We investigate arithmetic and combinatorial properties of the function a(n), which is the signed number of partitions of n into exactly two distinct part sizes, each occurring an odd number of times. We prove that a(n)≥ 0 for all n, establishing a positivity phenomenon for a signed partition function arising from a double Lambert series. Furthermore, we show that a(n) satisfies nontrivial divisibility properties modulo $3$. The results reveal unexpected arithmetic regularity in a family of partition functions defined by odd multiplicity constraints and restricted support.
Versions
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BibTeX
@misc{merca2026twoblock,
title = {{The two-block odd partition function}},
author = {Mircea Merca},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.33770},
eprint = {2609.33770},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.33770},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The two-block odd partition function
AU - Mircea Merca
PY - 2026
DA - 2026/09/27
PB - arXiv
DO - 10.48550/arxiv.2609.33770
UR - https://arxiv.org/abs/2609.33770
AB - We investigate arithmetic and combinatorial properties of the function a(n), which is the signed number of partitions of n into exactly two distinct part sizes, each occurring an odd number of times. We prove that a(n)≥ 0 for all n, establishing a positivity phenomenon for a signed partition function arising from a double Lambert series. Furthermore, we show that a(n) satisfies nontrivial divisibility properties modulo $3$. The results reveal unexpected arithmetic regularity in a family of partition functions defined by odd multiplicity constraints and restricted support.
ER -