int led1n3 = 2;
int led2n4 = 4;

void setup() {
  // put your setup code here, to run once:
  pinMode(led1n3, OUTPUT);
  pinMode(led2n4, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  for(int i=0; i<=10000; i=i+30){
    digitalWrite(led1n3, HIGH);
    delay(i);
    digitalWrite(led1n3, LOW);
    delay(i);
    digitalWrite(led2n4, HIGH);
    delay(i);
    digitalWrite(led2n4, LOW);
    delay(i);
  }
}