// For: https://forum.arduino.cc/t/missing-something-in-my-if-condition-code/1030094
//
// I am not 100% sure what it should do, so I made my own variation:
// The white leds blinks with 500 ms delay.
// The red leds blink together with the white led every fifth time.

const int whiteLedPin = 2;   
const int redLedPin = 4;
const int t = 500;
int c = 0;

void setup() 
{
  Serial.begin(115200);
  pinMode(whiteLedPin, OUTPUT);
  pinMode(redLedPin, OUTPUT);
}

void loop() 
{
  Serial.print(c);

  if (c == 4)               // 0,1,2,3 are normal, 4 is the fifth is special
  { 
    digitalWrite(whiteLedPin, HIGH);
    digitalWrite(redLedPin, HIGH);
    delay(t);
    digitalWrite(whiteLedPin, LOW);
    digitalWrite(redLedPin, LOW); 
    delay(t);
    Serial.println();
    c = 0;                 // reset the variable
  }
  else
  {
    digitalWrite(whiteLedPin, HIGH);
    delay(t);
    digitalWrite(whiteLedPin, LOW);
    delay(t);
    c = c + 1;
  }
}