There are 16 grid points evenly distributed in a square (each side has 4 grid points and 4 in the middle), so how many squares with grid points as vertices can be nested in total.
一个正方形中平均分布着16个格点(每个边长均有4个格点，中间4个)，这样，一共可以套出多少个以格点为顶点的正方形．
<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">9 + 4 + 1 + 4 + 2</gadget>
<output>20</output>

<result>20</result>