int LED1=8;
int LED2=7;
int LED3=6;
int LED4=5;
int x4=0,x3=0,x2=0,x1=0;
int ontime=2000;
int delaytime=3000;


void setup() {
  // put your setup code here, to run once:
  pinMode(LED1,OUTPUT);
  pinMode(LED2,OUTPUT);
  pinMode(LED3,OUTPUT);
  pinMode(LED4,OUTPUT);

}

void loop() {
  // put your main code here, to run repeatedly:
  for(int i=1;i<=16;i++)
  {
    digitalWrite(LED4,x4);
    digitalWrite(LED3,x3);
    digitalWrite(LED2,x2);
    digitalWrite(LED1,x1);
    delay(ontime);

    x4=!x4;

    if(i%2==0)
    x3=!x3;

    if(i%4==0)
    x2=!x2;

    if(i%8==0)
    x1=!x1;

    digitalWrite(LED4,LOW);
    digitalWrite(LED3,LOW);
    digitalWrite(LED2,LOW);
    digitalWrite(LED1,LOW);
    delay(delaytime);



  }
}