void setup() {
  // put your setup code here, to run once:
  for(int j=2; j<=19; j++) {
    pinMode(j, OUTPUT);
  }
  randomSeed(analogRead(A0));
}

void loop() {
  // put your main code here, to run repeatedly:
  int iStart = random(1,10);
  int iStop = random(11,20);
  for (int i=iStart; i<=iStop; i++) {
    digitalWrite(i, HIGH);
    delay(50);
    digitalWrite(i, LOW);
    delay(50);
  } 
  delay(200);
}