const int ledPins[] = {5,4,3,2};
const int numPins = 4;
static int arr[4];
void setup() {
  // put your setup code here, to run once:
    for (int i = 0; i < numPins; i++) {
    pinMode(ledPins[i], OUTPUT);
    digitalWrite(ledPins[i],LOW);
  }
}

void loop() {
  // put your main code here, to run repeatedly:
    for(int i=0;i<15;i=i+2){
      bnary(i);
      delay(1000);
  }
  delay(2000);
}
  void bnary(int n){
      for(int i=0;i<numPins;i++)
      {
        int x=n%2;
        arr[i]=x;
        n=n/2;
        if(arr[i]==1)
        digitalWrite(ledPins[i],HIGH);
        else
        digitalWrite(ledPins[i],LOW);
      }
  }