let sequence = [20, 40, 60, 80, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380];

​

function setup() {

  createCanvas(400, 400);

  background(255);

}

​

function draw() {

  shuffle(sequence);

  if(counter%20 == 0){

    colorMode(HSB);

    noStroke();

    fill(random(360), random(50, 100), random(90, 100));

    ellipse(random(sequence), random(sequence), 20);

  }

    counter++;

}

​

​