void setup() {
  Serial.begin(9600);
  randomSeed(analogRead(A0));
  pinMode(1, OUTPUT);
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);

}

void loop() {
  long rn=random(2,6);
  Serial.println(rn);
  digitalWrite(rn, HIGH);
  delay(250);
  digitalWrite(rn, LOW);
  delay(250);
}