int brightness = 0;
int pins[3] = {9,10,11};

void setup() 
{
  pinMode(9,OUTPUT);
  pinMode(10,OUTPUT);
  pinMode(11,OUTPUT);
} 

void loop(){
  for(int i = 0;i < 3;i++)
  {
   analogWrite(pins[i],brightness);
   ++brightness %= 4;
   delay(100);
  }
}