struct Step
{
  const uint8_t pin;
  const uint8_t time;
};

const Step steps[] =
{
  { .pin = 4, .time = 3 },
  { .pin = 3, .time = 2 },
  { .pin = 2, .time = 1 },
  { .pin = 3, .time = 2 },
};

const uint8_t steps_count = sizeof( steps ) / sizeof( Step );



void setup()
{
  pinMode( 2, OUTPUT );
  pinMode( 3, OUTPUT );
  pinMode( 4, OUTPUT );
}



void loop()
{
  static uint8_t step_id = 0;
  const Step & step = steps[ step_id ];

  digitalWrite( step.pin, HIGH );
  delay( step.time * 1000 );
  digitalWrite( step.pin, LOW );

  if ( ++step_id == steps_count )
  {
    step_id = 0;
  }
}