Ducci Sequence https://en.wikipedia.org/wiki/Ducci_sequence

ducciSequence.js

;(function() {
  "use strict";
  const hashIteration = seq => seq.join(",");

  const nextIteration = seq =>
    seq.map((num, index, array) =>
      Math.abs(num - array[(index + 1) % array.length])
    );

  function* ducciSequence(initialValue = []) {
    let prev = initialValue;
    let hash = hashIteration(initialValue);
    const iterations = new Set([hash.replace(/\d+/g, "0")]);

    yield prev;

    while (!iterations.has(hash)) {
      iterations.add(hash);
      yield (prev = nextIteration(prev));
      hash = hashIteration(prev);
    }
  }

  if (
    typeof module !== "undefined" &&
    module != null &&
    module.exports != null
  ) {
    module.exports = ducciSequence;
  } else if (typeof window !== "undefined") {
    window.ducciSequence = ducciSequence;
  }
})();