int ledPin[]={10,11,12,13};
int maxCount=16;


void setup() {
  // put your setup code here, to run once:
for(int i=0;i<4;i++)
{
  pinMode(ledPin[i],OUTPUT);  
}
}

void loop() {
  // put your main code here, to run repeatedly:
  for(int counter=0;counter<maxCount;counter++)
  {
    displayBinary(counter),
    delay(delayInterval);
  }
}

void displayBinary(byte numToShow)
{
  for(int i=0;i<4;i++)
  {
    if(bitRead(numToShow,i)==1)
      digitalWrite(ledPin[i], HIGH);
    else
      digitalWrite(ledPin[i], LOW);
  }
}