Groups containing only one rotation axis

If A₁ represents a rotation of an angle $\alpha$ around a given axis, A²₁, A³₁, $\ldots$, Aⁿ₁ = 1 are the symmetry operations corresponding to rotations of $2\alpha$, $3\alpha$, $\ldots$, $n\alpha$ = $360^{\circ}$ respectively, around the same axis; keeping in mind the values of $\alpha$ compatible with a lattice base system we obtain the groups named by the symbol n, i.e. 1, 2, 3, 4, 6.

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