During the festival, Xiaodong arranged 6 lanterns in a row, including 2 red lights and 4 green lights. If two red lights are not adjacent, how many different arrangement methods are there? (The "RGGGGG" and "GGGRGG" types are counted as one type)
节日期间，小东把6盏彩灯排成一列，其中有2盏红灯和4盏绿灯．如果两个红灯不相邻，则不同的排法有多少种．(其中"红绿红绿绿绿"和"绿绿绿红绿红"类型算作一种)
<gadget id="calculator">2 + 2 + 1 + 1</gadget>
<output>6</output>

<result>6</result>