Randy Jackson Quits American Idol

The dawg days are over at "American Idol" ... TMZ has learned Randy Jackson is officially LEAVING the judge's table ... but will still remain a part of the show as a "mentor."

We're told the honchos are keenly aware Mariah Carey isn't a fan of Minaj and doesn't want her at the table ... a fact producers LOVE because they think the conflict and tension will be good for the show. 

And ... we now know A.I. will once again go with a 4th judge ...  we're told producers are gunning for someone from the country music world for the third seat.  Seat number 4 is up in the air.

Finally, altough "A.I." wanted Diddy or Kanye West ... we're told they are definitely out of the picture.

Thiiiiiiiiis ... is getting intense.

Source: TMZ