Totient divisibility by $n^2+1$ and $n^2+2$

This note establishes exact classifications of the positive integers (n) satisfying two divisibility conditions involving Euler's totient function: [\varphi(n)\mid n^2+1\quad\Longleftrightarrow\quadn\in{1,2,3},] and [\varphi(n)\mid n^2+2\quad\Longleftrightarrow\quadn\in{1,2,4,6,14}.] The proofs use elementary number-theoretic arguments involving parity, prime factorization, and (2)-adic valuations. A computational verification using an exact totient sieve is also provided, together with a Python script for reproducing the exhaustive checks up to (2\times10^7). The note additionally records computational observations for related divisibility conditions of the form (\varphi(n)\mid n^2+c), without claiming complete classifications for those cases.

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Publication Details

Journal
Zenodo (CERN European Organization for Nuclear Research)
Published
2026-11-09
DOI
https://doi.org/10.5281/zenodo.24063877
Primary Topic
Analytic Number Theory Research
Type
article
Field-Weighted Citation Impact
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article

Totient divisibility by $n^2+1$ and $n^2+2$

James Freeman
Zenodo (CERN European Organization for Nuclear Research)
Analytic Number Theory Research
article

Totient divisibility by $n^2+1$ and $n^2+2$

James Freeman
article en

Abstract

This note establishes exact classifications of the positive integers (n) satisfying two divisibility conditions involving Euler's totient function: [\varphi(n)\mid n^2+1\quad\Longleftrightarrow\quadn\in{1,2,3},] and [\varphi(n)\mid n^2+2\quad\Longleftrightarrow\quadn\in{1,2,4,6,14}.] The proofs use elementary number-theoretic arguments involving parity, prime factorization, and (2)-adic valuations. A computational verification using an exact totient sieve is also provided, together with a Python script for reproducing the exhaustive checks up to (2\times10^7). The note additionally records computational observations for related divisibility conditions of the form (\varphi(n)\mid n^2+c), without claiming complete classifications for those cases.

Zenodo (CERN European Organization for Nuclear Research)
Analytic Number Theory Research
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