int redPin = 3;

void setup() {

  // put your setup code here, to run once:
pinMode(3, OUTPUT);

}

void loop() {
  // put your main code here, to run repeatedly:
  for(int brightness = 0; brightness<256; brightness++)
  {
    analogWrite(redPin,brightness); //increases
    delay(50);
    if(brightness==255)
    {
      digitalWrite(redPin, HIGH);
      delay(1000);
      digitalWrite(redPin,LOW);
      delay(1000);
      
    }

  }

  for(int brightness = 255; brightness>-1; brightness--)
  {
    analogWrite(redPin,brightness); //increases
    delay(500);
  }

}