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The focus of this paper is on the study of specific circle formations known as orthogonal Pappus chains and the related incidence results that involve points of tangency between the circles in the construction. These chains give rise to new circle families, with their centres on a conic. The paper also explores similar questions for Steiner chains, although it is demonstrated that orthogonality cannot be defined for them. Nonetheless, explicit examples are provided, exhibiting comparable incidence results and raising whether two Steiner chains that share a common circle in the chains possess this property.

We consider the group action of the automorphism group $\I_n=\aut(\Zz_n)$ on the set $\Zz_n$, that is the set of residue classes modulo $n$. Clearly, this group action provides a representation of $\I_n$ as a permutation group acting on $n$ points. One problem to be solved regarding this group action is to find its cycle index. Once it is found, there appears a vast class of related enumerative and computational problems with interesting applications. We provided the cycle index of specified group action in two ways. One of them is more abstract and hence compact, while another one is basically procedure of composing the cycle index from some \textit{building blocks}. However, those \textit{building blocks} are also well explained and finally presented in very detailed fashion., Comment: 11 pages