int i = 0;
int flag = 0;

void setup(){
  Serial.begin(9600);
  pinMode(3,OUTPUT);
  pinMode(4,OUTPUT);
  pinMode(5,OUTPUT);
  pinMode(7,OUTPUT);
  pinMode(2,INPUT_PULLUP);
}

void loop(){
   if(digitalRead(2)==LOW && flag==0)
    {
      i++;
      flag = 1;
      Serial.println(i);
      delay(150);
    }
   if(digitalRead(2)==HIGH && flag==1)
    {
      flag = 0;
    }
   if(i>=6)
    {
      digitalWrite(13,!digitalRead(13));
      i = 0;
    }

    switch (i) {
    case 1:
      digitalWrite(3, HIGH);
      delay(200);
      digitalWrite(3, LOW);
      break;
    case 2:
      digitalWrite(4, HIGH);
      delay(200);
      digitalWrite(4, LOW);
      break;
    case 3:
      digitalWrite(5, HIGH);
      delay(200);
      digitalWrite(5, LOW);
      break;
   case 4:
      digitalWrite(7, HIGH);
      delay(200);
      digitalWrite(7, LOW);
      break;
   case 5:
      digitalWrite(3, HIGH);
      digitalWrite(4, HIGH);
      digitalWrite(5, HIGH);
      digitalWrite(7, HIGH);
      delay(200);
      digitalWrite(3, LOW);
      digitalWrite(4, LOW);
      digitalWrite(5, LOW);
      digitalWrite(7, LOW);
      break;
  }
}