Find a certain law, and fill in the appropriate number in the brackets of the number in the following line to make it conform to the corresponding law. 2, 6, 12, 20, how much, 42.
寻找一定的规律，在下面一行数的括号里填上适当的数，使其符合相应的规律．2，6，12，20，多少，42．
<gadget id="calculator">5 * 6</gadget>
<output>30</output>

<result>30</result>