A={1,3,6,9,12} \mathrm {A = \{1, 3, 6, 9, 12\}}A={1,3,6,9,12}
A={3,6,9,12}\mathrm {A = \{3, 6, 9, 12\}}A={3,6,9,12}
A={3,6,9,12,15}\mathrm {A = \{3, 6, 9, 12, 15\}}A={3,6,9,12,15}
A={3,5}\mathrm A = \{3, 5\}A={3,5}