function setup() {

  createCanvas(400, 400); //create the canvas

  frameRate(1); //draw slow

}

function draw() {

  num =  pow(3,x); //num = 3^x 

  background(0)//set a black background

  fill(255);//fill boxes with white

  for(let i = 1; i < num; i++){//for loop to draw 3^x boxes

    rect(random(395),random(395),5,5)//draw rectangle in random location

  }

  fill(255)//make a white rectangle diameter text

  rect(330,0,100,20)//rectangle for diameter text

  fill(0)//make the text black

  text(str(num),350,12)//diamter text box

  x = x+1;//increase the exponent by 1

  if(x == 12){//make sure that the animation loops and doesn't crash

    x = 0;//reset x

    background(255)//reset background

  } 

}