Do the following operations on a natural number: if it is an even number, divide it by 2, if it is an odd number, add 1, and so on until the number is 1 and stop. Then, how many numbers are there that become 1 after 9 operations?
对一个自然数作如下操作：如果是偶数则除以2，如果是奇数则加1，如此进行，直到得数是1时停止．那么，经过9次操作变为1的数有多少个．
<gadget id="calculator">13 + 8</gadget>
<output>21</output>

<gadget id="calculator">21 + 13</gadget>
<output>34</output>

<gadget id="calculator">34 + 21</gadget>
<output>55</output>

<result>55</result>