\[\boxed{\mathbf{260.}}\]
\[\textbf{а)}\ A = \left\{ 2;4;6 \right\}.\]
\[\textbf{б)}\ A = \left\{ 1;2;3;4 \right\}.\]
\[\textbf{в)}\ A = \left\{ 3;4;5;6 \right\}.\]
\[\textbf{г)}\ A = \left\{ 2;3;4;5 \right\}.\]