Look at the sequence to find the pattern -3, 6, -9, 12, -15, 18... May I ask what the 1007th number is.
看数列找规律-3，6，-9，12，-15，18…请问第1007个数字是多少．
<gadget id="calculator">1_007 * 3</gadget>
<output>3_021</output>

<result>3_021</result>