n3+π7\frac{n}{3}+\frac{\pi}{7}3n+7π
nπ3+π7\frac{n \pi}{3}+\frac{\pi}{7}3nπ+7π
n3+π9\frac{n}{3}+\frac{\pi}{9}3n+9π
nπ3+π9\frac{\mathrm{n} \pi}{3}+\frac{\pi}{9}3nπ+9π