int segPins[7] = {8,7,6,5,4,3,2}; // reverse order
int buttonPin = 9;

int lastNumber = 0;

// Segment patterns for numbers 1–6 (a,b,c,d,e,f,g)
byte numbers[6][7] = {
  {0,1,1,0,0,0,0}, // 1
  {1,1,0,1,1,0,1}, // 2
  {1,1,1,1,0,0,1}, // 3
  {0,1,1,0,0,1,1}, // 4
  {1,0,1,1,0,1,1}, // 5
  {1,0,1,1,1,1,1}  // 6
};

void setup() {
  for(int i=0;i<7;i++){
    pinMode(segPins[i], OUTPUT);
  }

  pinMode(buttonPin, INPUT_PULLUP);

  randomSeed(analogRead(0)); // randomness
}

void displayNumber(int num) {
  for(int i=0;i<7;i++){
    digitalWrite(segPins[i], numbers[num-1][i]);
  }
}

void loop() {

  if(digitalRead(buttonPin) == LOW) {

    int newNumber;

    do {
      newNumber = random(1,7);
    } while(newNumber == lastNumber); // no repeat

    lastNumber = newNumber;

    displayNumber(newNumber);

    delay(300); // debounce
  }
}