Xiao Ming goes from the first floor to the second floor, a total of 8 steps, and he can cross at most three steps at a time, so how many ways does he have to walk from the first floor to the second floor?
小明从一楼到二楼，一共8级台阶，他每次最多跨三级，那么他从一楼到二楼，一共有多少种走法．
<gadget id="calculator">2 + 4 + 7</gadget>
<output>13</output>

<gadget id="calculator">4 + 7 + 13</gadget>
<output>24</output>

<gadget id="calculator">7 + 13 + 24</gadget>
<output>44</output>

<gadget id="calculator">13 + 24 + 44</gadget>
<output>81</output>

<gadget id="calculator">1 + 2 + 4 + 7 + 13 + 24 + 44 + 81</gadget>
<output>176</output>

<result>176</result>