int pin2 = 2;
int pin3 = 3;
int pin4 = 4;
int pin5 = 5;
int pin6 = 6;
int pin7 = 7;

void setup(){
  pinMode(pin2, OUTPUT);
  pinMode(pin3, OUTPUT);
  pinMode(pin4, OUTPUT);
  pinMode(pin5, OUTPUT);
  pinMode(pin6, OUTPUT);
  pinMode(pin7, OUTPUT);
}

void loop() {
   digitalWrite(pin2, HIGH);
   delay(50);
   digitalWrite(pin2, LOW);
   delay(50);

   digitalWrite(pin3, HIGH);
   delay(50);
   digitalWrite(pin3, LOW);
   delay(50);

   digitalWrite(pin4, HIGH);
   delay(50);
   digitalWrite(pin4, LOW);
   delay(50);

   digitalWrite(pin5, HIGH);
   delay(50);
   digitalWrite(pin5, LOW);
   delay(50);

   digitalWrite(pin6, HIGH);
   delay(50);
   digitalWrite(pin6, LOW);
   delay(50);

   digitalWrite(pin7, HIGH);
   delay(50);
   digitalWrite(pin7, LOW);
   delay(50);

   digitalWrite(pin6, HIGH);
   delay(50);
   digitalWrite(pin6, LOW);
   delay(50);

   digitalWrite(pin5, HIGH);
   delay(50);
   digitalWrite(pin5, LOW);
   delay(50);

   digitalWrite(pin4, HIGH);
   delay(50);
   digitalWrite(pin4, LOW);
   delay(50);

   digitalWrite(pin3, HIGH);
   delay(50);
   digitalWrite(pin3, LOW);
   delay(50);
}