Remarks on some Fuchsian groups. (Q1762799)

The author defines some Fuchsian subgroups of the group of isometries of the upper half plane. Only two of these groups are Hecke groups which are generalizations of the well known modular group. The elements of these groups can be classified into two kinds as odd and even and the even elements form a subgroup of index 2. The author calculates the parabolic class number of these Fuchsian subgroups, by using the power subgroups of these Fuchsian groups.