There is a series of numbers 1, 7, 13, 19, 25... What is the 1998th number in this series of numbers.
有一串数1，7，13，19，25…这列数的第1998个数是多少．
<gadget id="calculator">1_998 - 1</gadget>
<output>1_997</output>

<gadget id="calculator">1_997 * 6</gadget>
<output>11_982</output>

<gadget id="calculator">1 + 11_982</gadget>
<output>11_983</output>

<result>11_983</result>