byte myMatrix[][4] = {
  {10,11,12,13},
  {14,15,16,17},
  {18,19,20,21}
};
void setup() {
  Serial.begin(115200);
  for (int8_t i=0;i<3;i++) {
    for (int8_t j=3;j>=0;j--) {
      Serial.print(myMatrix[i][j]);
      Serial.print("\t");
    };
    Serial.println();
  }

}

void loop() {
  // put your main code here, to run repeatedly:

}