In a story in the novel "The Da Vinci Code", there is a series of numbers in a mysterious sequence: 1, 1, 2, 3, 5, 8, ..., what is the eighth number in this sequence?
小说《达•芬奇密码》中的一个故事里出现了一串神秘排列的数：1，1，2，3，5，8，…，则这列数的第8个数是多少
<gadget id="calculator">5 + 8</gadget>
<output>13</output>

<gadget id="calculator">8 + 13</gadget>
<output>21</output>

<result>21</result>