Divisibility and sequence properties of σ⁺ and φ⁺
Inspired by Lehmer’s and Deaconescu’s conjectures, as well as various analogue problems concerning Euler’s totient function φ(n), Schemmel’s totient function S₂(n), Jordan totient function Jₖ, and the unitary totient function φ*(n), we investigate analogous divisibility problems involving the functions σ(n), σ⁺(n), and φ⁺(n). Further, we establish some interesting properties of the sequences {σ⁺(n)}ₙ₌₁^∞ and {φ⁺(n)}ₙ₌₁^∞, in particular, we prove that each of these sequences contains infinitely many arithmetic progressions of length 3.
Authors
- Sagar Mandal (ORCID: https://orcid.org/0000-0001-8256-4384)
Institutions
- Indian Institute of Technology Ropar (IN)
Publication Details
- Journal
- SHILAP Revista de lepidopterología
- Published
- 2025-12-01
- DOI
- https://doi.org/10.7546/nntdm.2025.31.4.899-907
- Primary Topic
- Advanced Mathematical Identities
- Type
- article
- Field-Weighted Citation Impact
- 0.00