​

function setup() {

  createCanvas(600, 600);

}

​

function draw() {

  background(0);

  next(n);

  let aL = a.length;

  let prevX = 0, prevY = height;

  for(let i = 0; i < aL; i++) {

    fill(255); stroke(255); strokeWeight(0.6);

    let newX = i*width/aL, newY = (height - a[i]*height/gtA);

    if(newY > height) {

      fill(255, 0, 0); stroke(255, 0, 0);

    }else if(prevY > height) {

      fill(255, 255, 0); stroke(255, 255, 0);

    }

    line(prevX, mod(prevY, height+1), newX, mod(newY, height+1));

    prevX = newX, prevY = newY;

  }

  n++;

}

​

function seq(n) {

  return (3**(a[0] ? (a[a.length - 1]) : 1) % 99) % 7;

}

​

function mod(x,y) {

  let ret = x % y;

  while(ret < 0) ret += y;

  return ret;

}

​

function next(n) {

  let an = seq(n);

  a.push(an);

  if(a.length > mxaL) a = a.slice(1);

  if(an > gtA) gtA = an;

}