int fan[8] = {9, 8, 7, 6, 5, 4, 3, 2};
boolean fan1,fan2,fan3,fan4;

void setup() {
  Serial.begin(57600);
  for (int i=0; i<8; i++)
    {
      pinMode(fan[i], OUTPUT);
      digitalWrite(fan[i], HIGH);
    }
    randomSeed(300);
}

void sequence(boolean fan1, boolean fan2, boolean fan3/*, boolean fan4*/, unsigned long time_)
  {
    digitalWrite(fan[0], fan1);
    digitalWrite(fan[1], fan2);
    digitalWrite(fan[2], fan3);
//    digitalWrite(fan[3], fan4);
    delay(time_);
  }

boolean repeat = true;
void loop() {
  
//  while((fan1&&fan2&&fan3&&fan4)||((!fan1)&&(!fan2)&&(!fan3)&&(!fan4))||repeat)
    while((fan1&&fan2&&fan3)||((!fan1)&&(!fan2)&&(!fan3))||repeat)
    {
      if (random(0,1000)<500) fan1=false;
      else fan1=true;
      if (random(0,1000)<500) fan2=false;
      else fan2=true;
      if (random(0,1000)<500) fan3=false;
      else fan3=true;
//      if (random(0,1000)<500) fan4=false;
//      else fan4=true;
      repeat = false;
    }
  repeat = true;  
  unsigned long time_ = random(4000,15000);
  //unsigned long time_ = 100;
  Serial.print(fan1);
  Serial.print(' ');
  Serial.print(fan2);
  Serial.print(' ');
  Serial.print(fan3);
  Serial.print(' ');
//  Serial.print(fan4);
//  Serial.print(' ');
  Serial.println(time_);
  sequence(fan1, fan2, fan3/*, fan4*/, time_);
}