There are 18 seats in a row in the auditorium. If A and B are to sit together, how many different ways can they sit in the same row?
会堂里一排有18个座位，要让甲、乙两人坐在一起，在同一排有多少种不同的坐法．
<gadget id="calculator">18 - 1</gadget>
<output>17</output>

<gadget id="calculator">17 * 2</gadget>
<output>34</output>

<result>34</result>