Why is it that {α | α = 120 ° + (2k + 1) · 360 ° K belongs to Z} is not 120 ° at the end edge?

Why is it that {α | α = 120 ° + (2k + 1) · 360 ° K belongs to Z} is not 120 ° at the end edge?

Although {α | α = 120 ° + (2k + 1) · 360 °, K belongs to Z}, all the elements in {α | α = 120 ° + K · 360 °, K belongs to Z} = {α | α = 120 ° + (2k + 1) · 360 °, K belongs to Z} ∪ {α | α = 120 ° + 2K · 360 °