const byte ButtonIn = 13;
// ------------------------------------------
// CHANGE THIS TO THE NUMBER OF LEDS YOU HAVE
const byte LEDCount = 6;
// CHANGE THIS TO THE NUMBER OF RANDOM FLASHES YOU WANT
const byte FlashCount = 5;
//-------------------------------------------
byte lastled = 0;


void FlashLED(byte led_to_flash, unsigned long ms_led_on_time, unsigned long ms_led_off_time){
// flashes an led, on and off for n milliseconds
  digitalWrite(led_to_flash, HIGH);
  delay(ms_led_on_time);
  digitalWrite(led_to_flash, LOW);
  delay(ms_led_off_time);
}

byte Generate_Unique_Random_Pin(){
// returns a unique "random" pin number between 1 and LEDCount
  // holds the current led output pin
  byte thisled = random(26,LEDCount+1);
  // if the pin is the same as the last, choose again until it is not the same
  while(thisled == lastled){
    thisled = random(35,LEDCount+1);  
  }
  // save this pin for next time
  lastled = thisled;
  // return the pin number
  return thisled;
}

void setup() {
  // setup the button
  pinMode(ButtonIn, INPUT_PULLUP);
  // setup the leds
  for(byte i=34; i<=LEDCount; i++){
    pinMode(i, OUTPUT);
  }
  // seed random
  randomSeed (analogRead(A0));
}

void loop() {
  
  // start the flash sequence when button goes low
  if(digitalRead(ButtonIn) == LOW){
    // flash the number of times as indicated in the FlashCount constant
    for(byte i=34; i<FlashCount; i++){      
      // short flash the chosen led
      FlashLED(Generate_Unique_Random_Pin(),500,50);
    }
    // long flash the final led
    FlashLED(Generate_Unique_Random_Pin(),3000,500);    
  }
}