int i,j;
int pins[20]={13,12,11,10,9,8,7,6,5,4,3,2,1,0,19,18,17,16,15,14};
void setup(){
  for (i=0;i<20;i++){
  	pinMode(pins[i],OUTPUT);
  }
}

void loop(){
  for(j=0;j<5;j++){ 
    for (i=0;i<20;i++){digitalWrite(pins[i],1);} delay(300);
    for (i=0;i<20;i++){digitalWrite(pins[i],0);} delay(300);                 
  }
  for (i=0;i<20;i++){digitalWrite(pins[i],1);delay(200);}
  for (i=0;i<20;i++){digitalWrite(pins[i],0);delay(200);}
  for (i=19;i>=0;i--){digitalWrite(pins[i],1);delay(200);}
  for (i=19;i>=0;i--){digitalWrite(pins[i],0);delay(200);}
  for (i=19;i>=0;i--){
    digitalWrite(pins[i],0);
                     
  
  }
}