int pinarr[][2] = { {10,13}, {11,12}, {12,11}, {13,10}, {6,9}, {7,8}, 
{6,7}, {5,6},};

void setup() {
  
  for (int c = 2; c < 14; c++) pinMode(c, OUTPUT);
}

void loop() {
  
  for (auto& b : pinarr) {
    for (auto& g : b) digitalWrite(g, HIGH);
    delay(77);
    for (auto& g : b) digitalWrite(g, LOW);
  }
}