Fill in the numbers according to the law: 1, 3, 7, 15, 31, how much, 127.
按规律填数：1，3，7，15，31，多少，127．
<gadget id="calculator">31 * 2</gadget>
<output>62</output>

<gadget id="calculator">62 + 1</gadget>
<output>63</output>

<result>63</result>