void setup()
{
Serial.begin(9600); 
for (int i=2;i<=13;i++)
{
pinMode (i, OUTPUT);
  }
}  
void loop()
{
 int rastgele=random(2,13);
 Serial.println(rastgele);
 digitalWrite(rastgele, HIGH);
 delay(100);
 digitalWrite(rastgele, LOW);
}