1, 3, 5, 7, ... are odd numbers starting from 1, what is the 2005th odd number among them.
1，3，5，7，…是从1开始的奇数，其中第2005个奇数是多少．
<gadget id="calculator">2_005 * 2</gadget>
<output>4_010</output>

<gadget id="calculator">4_010 - 1</gadget>
<output>4_009</output>

<result>4_009</result>