int redPin = 11;
int greenPin = 10;
int bluePin = 9;

void setup() {
  // put your setup code here, to run once:
  setRgb(0, 0, 0);
}

void loop() {
  // put your main code here, to run repeatedly:
  int Rgb[3];
  Rgb[0] = 0;
  Rgb[1] = 0;
  Rgb[2] = 2;
  for (int decrease = 0; decrease < 3; decrease +=1){
    int increase = decrease == 2 ? 0 : decrease + 1;
    for (int i = 0; i < 255; i +=1){
      Rgb[decrease] -= 1;
      Rgb[increase] =+ 1;
      setRgb(Rgb[0], Rgb[1], Rgb[2]);
      delay (20);
    }
  }
}

void setRgb (int red, int green, int blue){
  analogWrite(redPin, red);
  analogWrite(greenPin, green);
  analogWrite(bluePin, blue);
}