Article
Keywords:
finite abelian group; isolated subgroup; sum of element orders
Summary:
We say that a subgroup $H$ is isolated in a group $G$ if for every $x\in G$ we have either $x\in H$ or $\langle x\rangle \cap H=1$. We describe the set of isolated subgroups of a finite abelian group. The technique used is based on an interesting connection between isolated subgroups and the function sum of element orders of a finite group.
References:
                        
[2] Busarkin, V. M.: 
The structure of isolated subgroups in finite groups. Algebra Logika 4 (1965), 33-50 Russian. 
MR 0179249 | 
Zbl 0145.02904[8] Suzuki, M.: 
Group Theory. I. Grundlehren der Mathematischen Wissenschaften 247. Springer, Berlin (1982). 
MR 0648772 | 
Zbl 0472.20001