int leds[5] = {2, 3, 4, 5, 6};
int Zahl;

void setup() {
  // put your setup code here, to run once:
 for (int i = 0; i<5; i=i+1) {
  pinMode(leds[i], OUTPUT);
  }
 Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  Zahl = random (0,5);
  Serial.println(Zahl);

  digitalWrite(leds[Zahl], HIGH);
  delay(100);
  digitalWrite(leds[Zahl], LOW);
  delay(100);

}