The arrangement of a column of numbers is: 1, 5, 9, 13, 17, ..., in this way, what is the 51st number?
有一列数的排列是：1，5，9，13，17，…，照这样排下去，第51个数是多少．
<gadget id="calculator">51 - 1</gadget>
<output>50</output>

<gadget id="calculator">50 * 4</gadget>
<output>200</output>

<gadget id="calculator">1 + 200</gadget>
<output>201</output>

<result>201</result>