int rBtn = 2;
int rLed = 3;

int stage = 1; //what will the size of the combination at the start
int i = 0;

void setup() {
  // put your setup code here, to run once:
pinMode(rBtn, INPUT_PULLUP);
pinMode(rLed, OUTPUT);

Serial.begin(9600);
}

void loop() {

while(i < stage){
  if(digitalRead(rBtn) == LOW){
  Serial.println(); Serial.println(); Serial.println();
  Serial.println(i);
  Serial.println(stage);
  Serial.println(" random number(s)");
  i++;
  delay(400);
  }
}
delay(1000);
stage++;
i = 0;
Serial.println(); Serial.println();
Serial.println(stage);
delay(1000);

}