const byte PinLed [] = { 7, 5, 4, 6 };
const int  Nled       = sizeof(PinLed);

const unsigned long MsecInterval = 1000;
      unsigned long msec0;

unsigned long cnt;

enum { Off = LOW, On = HIGH };

// -----------------------------------------------------------------------------
void
loop ()
{
    unsigned long msec = millis ();
    if (msec - msec0 >= MsecInterval)  {
        msec0 += MsecInterval;

        cnt++;

        for (int n = 0; n < Nled; n++)
            digitalWrite (PinLed [n], cnt & (1<<n) ? On : Off);
    }
}

// -----------------------------------------------------------------------------

void setup (void)
{
    Serial.begin (9600);

    for (int n = 0; n < Nled; n++)  {
        pinMode      (PinLed [n], OUTPUT);
        digitalWrite (PinLed [n], Off);
    }
}