The arithmetic sequence is 2, 6, 10, 14..., what is the 100th item of this arithmetic sequence.
等差数列是2、6、10、14…，则这个等差数列的第100项是多少．
<gadget id="calculator">100 - 1</gadget>
<output>99</output>

<gadget id="calculator">99 * 4</gadget>
<output>396</output>

<gadget id="calculator">2 + 396</gadget>
<output>398</output>

<result>398</result>