There is a sequence: 1, 2, 4, 7, 11, 16, ... What is the 25th number in this sequence.
有一数列：1、2、4、7、11、16、…这列数列第25个数是多少．
<gadget id="calculator">1 + 24</gadget>
<output>25</output>

<gadget id="calculator">24 / 2</gadget>
<output>12</output>

<gadget id="calculator">25 * 12</gadget>
<output>300</output>

<gadget id="calculator">300 + 1</gadget>
<output>301</output>

<result>301</result>