Double Blink

void setup() {
  pinMode(13, OUTPUT);
  Serial.begin(115200);
}

unsigned long loopCount=0;
char c;

void loop() {
  if (Serial.available() >0) {
    while (Serial.available() > 0) {
      c = Serial.read();
      Serial.write(c);
    }
    Serial.write("\r\n");
    Serial.flush();
  }

  Serial.println(loopCount++);
  Serial.flush();
  digitalWrite(13, HIGH);
  delay(50);
  digitalWrite(13, LOW);
  delay(200);
  digitalWrite(13, HIGH);
  delay(50);
  digitalWrite(13, LOW);
  delay(2000);
}