R−{2π978,n∈Z}\mathbb{R}-\left\{\frac{2 \pi}{978}, n \in \mathbb{Z}\right\}R−{9782π,n∈Z}
R−{(2n+1)π978;n∈Z}\mathbb{R}-\left\{\frac{(2 n+1) \pi}{978} ; n \in \mathbb{Z}\right\}R−{978(2n+1)π;n∈Z}
R−{nπ489;n∈Z}\mathbb{R}-\left\{\frac{n \pi}{489} ; n \in \mathbb{Z}\right\}R−{489nπ;n∈Z}
R−{2nπ489;n∈Z}\mathbb{R}-\left\{\frac{2 n \pi}{489} ; n \in \mathbb{Z}\right\}R−{4892nπ;n∈Z}
